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Afaik know there's no keyways on the crank, so if you press the cranks appart there's no easy way to get them re aligned for reassembly ( if you go this way I'd really appreciate a good write up with plenty of pics :D)
what rods are you putting on? I went down this road as a thought process the best I could find wich have the correct big end width and daimeter but longer length was putting in a pair of cb100 k0 rods which are the same lenght as the cb200 ( they're longer than the cb175) or there's a yamaha 2s scooter which is longer again
 

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Discussion Starter #42 (Edited)
Afaik know there's no keyways on the crank, so if you press the cranks appart there's no easy way to get them re aligned for reassembly ( if you go this way I'd really appreciate a good write up with plenty of pics :D)
what rods are you putting on? I went down this road as a thought process the best I could find wich have the correct big end width and daimeter but longer length was putting in a pair of cb100 k0 rods which are the same lenght as the cb200 ( they're longer than the cb175) or there's a yamaha 2s scooter which is longer again
I will be meeting with one of the local vintage Honda pro's in the coming week(s), for the very reasons you mentioned. Hopefully he can accomplish this task, and allow me to watch and learn.. dunno yet. If yes, I will certainly provide details of the job. I have yet to come across any decent instructions/guidance for accomplishing this task. The CB175 K5 FSM is pretty straight forward... just says "remove and replace" (end of direction) and gives no reference to the wrist pin to connecting rod fit... maybe Clymers does? I will use your's and Steve's (66Sprint) recommendation previously discussed (pin to rod clearance) if I can't come up with hard data. If I can't get this job outsourced/accomplished by the local vintage pro, then it becomes just another DIY moment/challenge to overcome.

I am using NOS CB175 (K5) connecting rods. The small ends have to be sized (and trued) for the new piston pins as they don't come ready to go. The R/H rod small end was damaged by the previously mentioned piston kick-over (looks like some heat damage and the bearing surface was gouged). The old rods will be retained and a determination will be made later whether to OS the small end to accept "forcemate" bushings and sized to either 14mm or 13mm ID for usage on another build, or toss them. If your unfamiliar with the term "forcemate", its basically a cold work process used in aviation, for critical areas.

Also I will not be using those intake and exhaust valves with the slotted tulips in this build. I really don't like the idea of sharp edges exposed in the combustion area. I probably ought to ask "Honda Restorations" about them as they provided one set. In any case, they are not for this build.

NOTE: There are lots of used crankshafts out there on Ebay, but its critical that I have in spec (new) measurements on the connecting rod to piston pin fit. There's no way that could be guaranteed using Epray.

,,,,back to the house stuff, and practicing polishing/painting things :)

Cheers
 

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On the cb200 the flywheel pin is 26mm. The piston pin is 15mm the roller bearing opening in the conrod is 32mm and the distance between both is 80mm. So 7.5 + 16 + 80 = 103.5 mm for conrod length and it's width is 14mm both top and bottom.
The175's take a 14 mm gudgeon pin and are shorter in lenght (iirc it's around 94mm so c90 con rods fit and add 3mm )
since your pistions have a lower pin to crown hieght and you're stripping the cranks why not put a longer rod in
EUROPEAN ROD KITS
the xc125 has a 13mm small end but all other dimentions are correct but is 112mm long if you can cram 18mm in ( cb200 barrels and engine studs )
 

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Discussion Starter #44
On the cb200 the flywheel pin is 26mm. The piston pin is 15mm the roller bearing opening in the conrod is 32mm and the distance between both is 80mm. So 7.5 + 16 + 80 = 103.5 mm for conrod length and it's width is 14mm both top and bottom.
The175's take a 14 mm gudgeon pin and are shorter in lenght (iirc it's around 94mm so c90 con rods fit and add 3mm )
since your pistions have a lower pin to crown hieght and you're stripping the cranks why not put a longer rod in
EUROPEAN ROD KITS
the xc125 has a 13mm small end but all other dimentions are correct but is 112mm long if you can cram 18mm in ( cb200 barrels and engine studs )
Simo, that's a great list for the Rod Kits.. noted and saved :) A little ahead here, but let's see if I can show you a piece of the plan as it currently stands today (always dynamic though). Importantly, this is not a race build.

I will retain the new CB175 connecting rods. The pictures below will shows rotational weight avoidance/savings between the original and replacement pistons. Using longer rods to maintain crown deck fit would most likely add rotation force weight, and create other design/weight/costs issues. Yes, the piston crown would be sitting below the cylinder head deck by approx 1.2mm << this is a rough measurement.. I haven't had my coffee yet haha.

The idea at the moment to correct this off-set is to use a thinner gasket between the upper case half in combination with shaving the bottom of the cylinder barrel. This will lower the entire upper assembly downward; will have to keep an eye on the oil feed, cam chain tension and will probably have to use thicker washers to the cylinder head capture nuts so they don't bottom out. I am not too concerned about crank case pressures as the kick start is going to be removed/replaced with an additional crankcase breather line. I can retain the stock oil check/fill cap this way :)

NOTE: I located and will be replacing the original cylinder head. If you recall, the original head requires time serts (stripped spark plug threads), an increase in combustion chamber cc's due to damage caused by the choke plate that went bouncing around the combustion chamber, damaging valve seats and a one valve guide. The used $40 head (in most excellent condition) far out-weighed the repair costs of the original head, although I will keep it for some experimental play :)

Here's a few comparison pictures:
- combined weight of the original and replacement pistons and pins
- piston heart line to crown distance (visual)
- pin lengths (NOTE: The old pin although longer, is thinner than the new pin.
- Old pin approx 1.5mm thick walls (length; 41.7mm)
- New pin approx 2.05mm thick walls (length; 35mm)

Thanks for looking out after me! Its most appreciated !

Cheers
 

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All good
you can run no base gasket if you have to. You're going to have lower compression ratio with the lower crown on the t bolts so you could consider shaving the head as well. Taking anything off anywhere will effect the cam chain tension and timing . If you need a new head a cb200 head bolts on ,has the same valves, better guides and oil seals, larger fins for cooling , takes the cb175 cam journals (there's an oilling mod required but that's just a 3mm hole drilled in the correct place)
 

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Discussion Starter #46 (Edited)
All good
you can run no base gasket if you have to. You're going to have lower compression ratio with the lower crown on the t bolts so you could consider shaving the head as well. Taking anything off anywhere will effect the cam chain tension and timing . If you need a new head a cb200 head bolts on ,has the same valves, better guides and oil seals, larger fins for cooling , takes the cb175 cam journals (there's an oilling mod required but that's just a 3mm hole drilled in the correct place)
I was thinking of using hondabond between the upper case half and lower cylinder base to help obtain zero deck, but am concerned about it leaking into and sealing/blocking the upper oil feeds... its on my watch out/test list.

There "should be" no reason for compression ratio to drop below 9:1 even though the upper crown (top) of the new piston displaces less volume. The 57mm piston will be pumping into the stock displacement combustion chamber. If pretending to use the same displacement of the upper top of the stock piston, on the new 57mm piston, the compression would raise to a touch over 11:1.

EDIT: The above paragraph is incorrect - Simo is correct - the C/R drops more than I was estimating.. the way out is to either stroke the engine or weld up the head/shave head.

I have to look at what Patrick determined the displacement of the new piston crown (top) was as I have not measured that (yet). I will use the "Sheldon Cooper, Big Bang Theory" displacement measuring method when I get around to it. And, if the C/R ends up lower than desired, the next step is head gasket thickness reduction, but maintain squish. In all honesty, my target is a slightly lower C/R than stock. Its a juggling act for sure! Math is fun :)

PS: I will stick with the 175 head.
 

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Discussion Starter #47 (Edited)
Connecting rod replacement / Crankshaft disassemble-reassemble / Crankshaft balance

I looked at the crankshaft this morning to see what would be required for DIY situations, or, if I have to explain correctly what is may be required to a machinist if I am unable to have this done by a local vintage pro.

If I understand correctly the crankshaft has no key way references itself, but, when looking at the crankshaft, it appears it has potential EXTERNAL key way alignment capability. There are four (4) slots aligned across the length of the crankshaft when its assembled. A machined bar stock could be manufactured and placed into these 4 slots to ensure alignment during reassembly. Does this sound reasonable Yes/No ??

CS Slots.jpg

The connecting rod replacement procedure would be to remove and replace one connecting rod at a time by removal and re-installation of one end piece of the crankshaft at a time. To install the new connecting rod, apply lubriplate to the the crankshaft and freeze it using dry ice/nitrogen? house freezer?. Heat the removed end piece to 400-500F, then press it onto the frozen crankshaft. Use the machined bar/rod to maintain alignment during the press procedures. Use/duplicate the same procedure to replace the remaining connecting rod.

After changing out the connecting rods, a static re-balance of the crankshaft might be required, since the replacement pistons/pin and associated weights are less than what the stock pieces were, and, to account for possible weight differences between the old and new connecting rods. (See thread #44 above for piston weight differences)

The plan would be to place the crankshaft large bearings on a heightened V-block set up, add the piston pins, pistons (with rings) to the ends of the connecting rods to see where the balance is.

Currently without the end items installed on the connecting rods, the crankshaft will rotate quickly on its own by bringing the empty small end of the connecting rod close to the crankshaft reflecting an out of balance condition. Where would the best place be to remove material if the crankshaft needs to be statically balanced? What do you think?
 

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Discussion Starter #49 (Edited)
Teazer on do the ton has first hand knowledge of rebuilding 175 cranks
Thanks Simo !
I remember reading Teazer was toying with converting a 360 crank to 180 for his racing endeavors. I don't have an account over at DTT, but enjoy reading some of the project logs there. Will see if anything pops up here at HT over the next couple days.

If I don't get interrupted with additional wife honey do's I should be visiting with the vintage folks in Wichita later this week... and if that fails, I'll take it on. Fear no evil haha.

PS: Piston pin to rod end clearances are in the CB200 FSM... I will transpose them for a 14mm fit. Yea haw
 

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Discussion Starter #50

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Discussion Starter #51 (Edited)
Nice weather today, got a few things accomplished with media and soda blasting; installed modern grips and controls; the donor fuel injection system from our Formula SAE days is disassembled, cleaned.. will set the flow rates later down the road (little more number crunching). Still juggling the electrical power source issue (currently in mock up and test - without this, FI is not possible), engine internal oil control system changes, additional closed loop oil/water cooled forced air induction system, a home brew dyno test system that can handle steady state operation (in design) and number of other things were actively playing with in design/development mock-up and test. All the pieces and parts required for this puzzle are in hand (as it stands today).

The build approach is done in stages. As tests are verified/validated, I'll will let you know about them. Biggest "personnel goal" is to retain stock appearances as much as possible. This IS NOT a Do The Ton cycle, but IS to be a "most happy" Do the 1/2 Ton cycle (rolling test bed). Between writing/arranging music stuff and this project I be happy. I don't like the wifes never ending honey do's haha.

ETC April 2016, 45th birthday for the cycle (lighting 3 candles and facing them to the east, saying a prayer)

Harbor Freight has a 20 ton press on sale with their super coupon for $149.99. I can mess that crankshaft up as well as the next guy, so were going to bring that puppy home tomorrow. Snow, ice & low temps rolling back in this eve for the next week of so.

Cheers and Adio's for a bit
Q
 

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Discussion Starter #52
While the snow falls, been reading up on the differences between the various carburetors between the CB125T thru CB200 series. I am curious if anyone has successfully used the 11,000 rpm CB125 twin's 26mm Keihin Carbs in place of the 10,500 rpm CB175's (K5) 20mm carbs. I have to be missing something here (beyond a loose screw?)
 

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Two 26 mm carbs will be WAY too large for a stock engine, although I did have some luck using two CB125S carbs which are 22mm venturi size.....
I DID have to fabricate new manifolds for them, and port match those to the heads however.....

Two 26 mm carbs were stock on the 305's and the SL350 on the K1 and K2 versions......

There is a LOT more involved in the RPM difference than carburetion......
 

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Discussion Starter #54
Two 26 mm carbs will be WAY too large for a stock engine, although I did have some luck using two CB125S carbs which are 22mm venturi size.....
I DID have to fabricate new manifolds for them, and port match those to the heads however.....

Two 26 mm carbs were stock on the 305's and the SL350 on the K1 and K2 versions......

There is a LOT more involved in the RPM difference than carburetion......
Yup, lots of complexities involved, and I have no desire to use/test these on this build.

Curiosity got the better part of me as I was noticing in this series of Honda twins, the larger the engine cc, Honda installed smaller carbs (not necessarily jetting etc). It was starting to make me think a 1k cc twin would need just a pin hole for air haha. I hadn't noticed anyone going that large for their 175 race bikes.

I do like the idea of using 22mm over the 20mm for a near stock CB175. Not plug and play, but doable.

Thanks Steve (66Sprint), most appreciated !
 

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The other thing to look at is the float hight the higher the fuel (lower the hight) the greater the fuel pressure . So the pw22's on my 175 have a 28mm float but the same carb might be set up with a different jet/float configuration on a different bike
The smaller the venturi the faster the air flow (up to a point)
so smaller carbs give better low end, since they they're able to effectively fill the cylinders at lower speeds at WOT they choke the engine
large carbs have slower velocity which is why a race bike might need a 3k idle speed since they need the rpm to keep the intake velocity up enough to run
Heres a good read...
http://www.hondatwins.net/forums/1-project-logs/30430-zeke-s-cb175-victoria-15.html
 

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Discussion Starter #56
Its always good to review Patrick's HT build and the more complete logs at DTT that cover the Lucky build also.

Intended for evil Harley builders, I found the technical information at this link informative. Folks here at HT would undoubtedly "SCREAM NO NO" at the recommended piston assembly procedures (regarding pre-lube) as its 180 out from recommendations here. I am not sure what to make of this big difference of opinion. The cam section has good informative explanations concerning the flow (air) of things and other useful information (squish etc).

NRHS - High Performance for your Harley Twin Cam, Evolution, Sportster or Buell!

In the end its all a balancing act, and that's the challenge :)
 

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Discussion Starter #57 (Edited)
Short update:

The 20 ton press is in the garage. Machine shop - crankshaft alignment tool is being manufactured; aligning and reaming to size the small ends of the connecting rods; bottom cylinder milled to maintain zero deck for the replacement pistons and bored to accept the replacement 500/f liners; 500/f liners dimensions corrected (total length/upper lip thinned/re-chamfer the bottom) as previously discussed. The cylinder will then be sent to another shop for boring the liners for piston fit and a couple other things the following week.

Simo, I will take good pictures and post the crankshaft alignment tool prior to separating the crankshaft. I might have to come up with thinner arbor plates; the ones that come with the press appear to be too thick for this job.. dunno yet. Should be towards the end of next week.

Cheers
 

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Discussion Starter #60 (Edited)
Pic's of the special tool to help keep crankshaft alignment. It is precision built and will most likely fit this crankshaft only. It has to be tapped into place for use, but in the pictures is just resting in place. It is tapered on the ends, and where the main crankshaft bearing are, the tool will be ground down a tad to insert a large metal band clamp to secure the tool in place. In the pictures its not centered (lf/rt).. just resting for now. I will most likely not get to this task until next week.

This is the special tool. It will fit only one way (direction) onto the crankshaft

Tool1_Rev1.jpg

Tool3_Rev3.jpg

Tool2_Rev2.jpg

Here are pictures of the completed cylinder assembly, with liners, and pistons installed (without the rings). The liners are bored for the 57mm T-Bolt slipper piston with a 400 grit cross-hatch. Its officially a 209cc engine. (same as Patrick's, Triumpsuper3 "Zeke" build)

NOTE: Mike the machinist out of nowhere said "what ever you do, DO NOT put any lubrication of any kind on the liner or piston skirt area" when I put it back together. Just do the clinical clean-up prior to assembling. How about that !!

NOTE: At 62 I'm the youngest guy in the shop..

There was one change in the CB500/F cylinder liner plan. The upper lip thickness was maintained by increasing the bore depth into the cylinder. The aft/inboard upper lip was notch out for stud clearance. It was better, faster, cheaper than thinning and reducing the diameter of the lip.

The bottom of the cylinder was milled down so that zero deck could be maintained. In the picture (shown at TDC) the pistons will appear slight above zero deck, but that's because they are slightly tilted as they have no rings and the base gasket is not installed (some illusion from reflections also). With rings and base gasket installed, zero deck should be maintained. A copper gasket will replace the standard head gasket. I will check "squish" and valve clearances later in the project.

Zero Deck 1.jpg


The upper case half was bored out to accept the CB500/F lower cylinder liners, poking out 25mm (same as the stock 175 lower liners). No crankshaft bearing support material was removed. The base of the liners were re-chamfered to ease piston installation.

Cylinder Liner Base_Rev1.jpg

The camshaft is at the machine shop. An adjustable sprocket is being machined for a +1 and -1 tooth throw. Once that's done the camshaft and the rockers will go off to another shop in Washington State for nitrite processes etc. The cam lobes are to remain stock.

The machine shop I use (less than 10 minutes away), has a nice Serdi valve machine. I made a decision to go 1 size diameter over on the exhaust valves and possibly the intake valves (not decided yet). I don't think I need to open the intakes, but from what I understand the exhaust is a bit constipated. There are no plans to port anything. Kibblewhite valves (with keepers), and possibly the valve train spring parts will be used. This task won't be done for a couple months. The combustion chamber/piston crowns will have Cerakote "Piston Coat" for heat/detonation protection applied and another Cerakote product "Micro Slick" applied for piston skirt protection (less friction). We have a dealer in Wichita, but I will most likely do this myself.

http://www.cerakotehightemp.com/gall...-Film-Coating/

I have not set the piston ring gaps yet. I could use some advise on the gaps... should I use the std CB200 ring gaps as a reference or ??

If you see any red flags by all means YELL !!

Cheers
 
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