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Discussion Starter #1
Bike: '79 Honda CB400 TII Hawk

Background: I've been having idle issues lately so I'm doing a carb clean and consequentially a rebuild because why not. I figured since I was going through all of that anyways, I should go ahead and rejet the carbs (from stock) for a new set of mufflers (stock headers) at the same time. (leaving airbox stock...for now)

Initial plan: 1. get mufflers off, put new ones on (17" reverse cone) 2. rejet carbs 3. test and go from there

What happened: So I tried as I might but the mufflers would not come off; I'm not sure if the gasket seal is just so gunked up that it won't come loose or what but short of torching it I've tried everything that I could think of/find on this forum. My next thought was to go ahead and just remove the entire header/muffler system and work the mufflers off that way. (And maybe go to a 2-1 with the mac system? ...although I've heard of some complaints here and there...)

Dilemma: Unfortunately the pipes with the muffler still attached can't maneuver around the brake pedal, as I should have noticed...

Should I:
1. Torch the mufflers off, go from there and either stick the new mufflers on or go to a 2-1.
2. Remove the brake pedal but in order to do that will I have to remove the entire rear end of the bike, tires/brake/anything else...?
3. Just reattach the pipe and concentrate on the carb clean.

All I wanted to do was to get the carbs all cleaned and synched so I could at the very least get the bike running...but I just had to go and try my hand at changing the exhaust system...

ps: which carb cleaner (for a soak) should I get?
 

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On the carbs, there is a sticky in the Fuel section on cleaning and rebuilding the VB carbs, it's written for the later versions so some doesn't apply to your VB21's.
Stock air box and essentially stock exhaust will only need the primary main jet increased one size. Another sticky in Fuel covers all the known carbs and stock jetting.
Once you remove the exhaust you've lost all the leverage for removing the mufflers. I'd put it back together to get the leverage. The gasket seal hardens and glues the 2 parts together. 2 people needed, one to hold the bike and apply heat frpm a torch to the joint, 2nd person leaning, twisting, prying, pulling on the muffler to break it loose.
Sounds like you're buying the Emgo reverse cone mufflers that can be repacked. You will definitely want to repack them using the FMF white muffler packing. You may want to drill some of the baffle holes to cut the higher pitch sounds also like this
201_5998-001 (1).JPG
The only alternate 2-1 system to the MAC is a MOTAD sold by David Silver Spares, not specifically for your model so the muffler mounting will need some work.
 

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Discussion Starter #3
Thanks for the reply. I bolted the power chamber and pipes back on and now all I need is a friend with a torch. What part of the exhaust did you drill baffle holes in? Or should I make my own? And I'm assuming based off everything I'm reading that the exhaust change warrants its own carb-rejet outside the one jet size increase I'll be doing? In the meantime I'll need to pick up some cleaner and get the carbs cleaned and rebuilt at the very least.

And yup, I've read through and bookmarked all those stickies plus some other useful threads. One question: Can I use the same allen head replacement sizes you mentioned in your stickie for my VB21?
 

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Another useful tool is a rubber oil filter ratchet. You can two sizes for a total of less than six bucks at Harbor Freight if you use their 20% off coupon. Not everything from there is crap. The ratchet allows you a stronger grip on the exhaust, and at inconvenient to hold places that you normally would not be able to access easily.
 

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