Honda Twins banner

1 - 10 of 10 Posts

·
Registered
Joined
·
224 Posts
Discussion Starter · #1 ·
The left cylinder has 165 with the carbs off. Went to do the right one which is the one that was not firing and I couldn't get the tester to screw in. I get a flashlight and look close to find the first three or four threads gone or almost anyway. Is there such thing as a long reach tester? If there were and the compression was the same I would let it go for a while. I really don't like or want to put inserts in. Has anyone here used them with success and had confidence in them? It is starting to look like I didn't get as good a deal as I thought. Top end job with possible replacement head that I will have to job out.
 

·
Registered
Joined
·
13,085 Posts
Nah, you probably won't have to replace the head. Pulling a plug isn't something we always think to do during a purchase, especially when the bike runs good and all seems well, and my 450 had a plug hole that needed to be chased when I bought it. Mine is about like you describe, with the upper 3 or 4 threads pretty much thin or gone but the remaining threads below that are fine. I'm just careful when removing or replacing the plug, and my bike is running 11.6:1 pistons too and I have no issues. If yours is bad enough tat running a proper tap through it to clean it up isn't enough, then I'd suggest a timesert instead of a heli-coil
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #3 ·
I went to the local bike shop and he loaned me his compression tester that had longer threads. Basically I was just hoping both were about the same and I am not surprised they aren't. I have not adjusted the valves (which I am going to take a stab at tomorrow) and I only static timed the left cyl. His tester is a Motion-Pro and it only tested @ 125 psi on the left and 100 on the right. After I get the valves adjusted and timed again I will recheck. I have heard one or two people here say to reuse the hardware in the carbs because the new kits aren't as good. Just use the gaskets and washers and seals. I bought the kit with the floats as one of mine has gas in it and I will use both new floats. How close does the float adj have to be to 20mm? Hopefully I do all this and it will run pretty good. Hey dad you said you are running 11.6:1 pistons, I'm guessing you did a total motor rebuild. If I need a new top end job how far over stock can a cylinder go over, in case one of the PO's have already bored it? I finally watched your test blast, very cool. Red line speed shift fever, what was top speed there?
 

·
Registered
Joined
·
13,085 Posts
I'm not running stock carbs and haven't touched stock carbs in a very long time, but if the float level is supposed to be 20mm then you should have it damn close to that AFAIK. If you actually do have 25 lbs difference between cylinders, you could ride it for a while but it will eventually need a rebuild and the harder you ride it in the meantime, the sooner it will need to be done. Yes, the hard parts in carb kits often include the wrong jet sizes, the primary reason to re-use your OEMs. You should adjust the cam chain once you have the valve covers off as well so you can watch the front of the chain to see when it is tight before releasing the adjuster to tension the back of the chain, then do the valves. As for my bike - yes, it's bored 4mm oversize, which is equal to 16 over in factory increments. The factory increments are .25mm up to 4 sizes over, or 1mm max. Not likely you'll have to exceed that if you have to do a rebuild, unless someone before you had already gone to the factory max overbore. Even then, there are piston kits out there that are larger than 1mm over (and with stock compression ratio) but not nearly as large as mine. Top speed on that run was around 90 on the speedo (maybe a tad more), with whatever error exists in 45 year old gauges... :D the speedo face is in KPH but the working parts of the speedo are my original in mph, with 20/40/60/80/100 marked on the KPH face for my reference points. I bought the gauge set already cosmetically refurbed from an HT member in Canada with nice new faces and a voltmeter in the tach which has since lost segments and then stopped working, then I had to re-work the speedo because the needle started waving around wildly and the tach because the needle fell off... (nice job, huh)
 

·
Registered
Joined
·
1,364 Posts
I made my compression tester "threaded" part from an old spark plug (drilled out), JB weld and a air-compressor quick disconnect.. I use the same part for leak down testing...
I have installed "plug repair threads" that required then to be "seated"/hammered to bite the head so they don't come out.. installed with red loctite.. haven't had issues since..
Kinda like it, don't have to worry about stripped threads, crossed threads...
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #6 ·
ancientdad before I removed the covers I thought I did the cam chain adj by just loosening the lock nut then the bolt and tighten back. After I took the covers off the front is loose and the back seems tight. I think I seen where you should hand turn the motor over while the adj nut is loose then tighten back. That's not what you are talking about though is it? I'll look in the manual again.
 

·
Registered
Joined
·
1,364 Posts
I'm not positive.. but aren't cam chain adjusters / adjustments to be done with the motor / pistons in a Position where there is no "tension" from the valves on the chain??
 

·
Registered
Joined
·
224 Posts
Discussion Starter · #8 ·
In the book I have (CLYMERS) it reads in Tune-ups and periodic maintenance and again in Engine service, under Cam chain adjustment, "The cam chain will wear and loosen up in time, requiring adjustment. Loosen the locking nut on the tensioner adjusting bolt and then the adjusting bolt itself. A spring operated mechanism automatically adjusts the tensioner. Retighten the bolt and locking nut. Do not push on the tensioner push rod as this will only result in shortening the chain and roller life." Now under adjusting the tappet clearance you do have to have the timing marks on LF on compression stroke for left cylinder then turn counterclockwise 180* for adjusting the right side. But I'm almost sure I seen it some where, but I can't find it now, that when you are adjusting the tensioner to roll over the motor by hand till the front of chain has the least amount of slack, but I can't remember if that was before you loosen the nuts or while the nuts are loose. The front of my cam chain is loose while the back is tight and I did it like the book says. I think I will go turn it around to see if the front of chain gets tighter.
 

·
Registered
Joined
·
13,085 Posts
But I'm almost sure I seen it some where, but I can't find it now, that when you are adjusting the tensioner to roll over the motor by hand till the front of chain has the least amount of slack, but I can't remember if that was before you loosen the nuts or while the nuts are loose. The front of my cam chain is loose while the back is tight and I did it like the book says. I think I will go turn it around to see if the front of chain gets tighter.
The first thing you should do is relegate the Clymer manual to beer coaster or door stop status - you need a FSM (factory shop manual), as the aftermarket versions are often incorrect. It definitely is in this case... in a perfect world, the tensioner would take up the slack when you loosen the lock bolt (after loosening the lock nut, of course). However, and you'll notice this as you become more familiar with the animal that is the first production Japanese DOHC bike ever made, the force of opening valves overcomes the ability of the spring on the cam chain tensioner to do its job without some help - and not by forcing the rod on the tensioner, at least Clymer was right about that. With the valve covers and the alternator rotor cover off, turn the crank until you see one exhaust valve opening - that tensions the front of the chain - and then loosen the lock bolt to let the tensioner do its work on the intake side of the chain. That's how I've always done it and it never fails. Here's a link to the real thing - look for the download icon in the upper right

https://drive.google.com/file/d/0B8RLEMngUB63VVBENlJuTEhyeW8/edit
 
1 - 10 of 10 Posts
Top