Carb jetting

[2stroker]

If your air/fuel ratio is too lean will this affect rpms? I took the bike around the block and I wasn't giving it much but the rpms were getting real high so I shifted to 2nd and without barely any throttle the rpms went up so I had to shift to 3rd. This is within 100-200ft. Is this normal for hodakas?

I have a 28mm mikuni that have not changed anything inside and a universal, slip on UNI filter. Thats why I thought it was lean, and with an expansion chamber it needs more fuel over stock. When I'm getting off the line it just wants to pick up and go, there's no easing in to it and slowly letting the clutch out like I can do on all the other bikes I have. I've never ridden a hodaka so I have nothing to compare to.

[Dale]

No, this is not normal. You need to isolate the issue and resolve it for sure.

Do you have a small amount of play in your throttle cable? With the engine off, you should be able to feel a little slack when you first turn the throttle.

Does it idle okay and only does this when you give it gas and attempt to go? If so, it is either very lean or you have an air leak. If it is sucking air around your manifold, it will rev and not idle down like it should. Air leaks are bad. Do you have the means to perform an air leakdown test?
Dale

[admin]

Great advise Dale !! Perfect.

[2stroker]

Thanks for the reply. Yes there is some free play in the throttle. It idles, as low as I can get it without it stalling out. Before it was leaking at the head and wouldn't idle at all but I think I fixed it. My clutch engages at the very last minute at the end of the lever, so I'm reving it a little and slow releasing the lever and once the levers completely out, the rpms pick up, i think. I'll probably get bigger jets and see if that helps it. I don't think the manifolds leaking since I just put fresh gaskets all around. How do you do a leak down test? There might be a very small leak somewhere since I see small droplets of oil after running it (on the topside of engine, not bottom).

[Dale]

It sounds like you might have a clutch or clutch adjustment issue too, but oil droplets is a big red flag for an air leak. I would not run it at all until you can fix that. The leak down test can be performed with parts put together from most any hardware and auto parts store. There is a procedure under Technical Tips here on the Strictly Hodaka web site. Look for the Hot Tips section. It is hidden in an article called "Do it yourself Mini Buff".
Dale
Added note: The parts listed in the Mini Buff article can be substituted for by anything that will hold air. A freeze plug for the exhaust opening works great. Smear a small amount of grease on the rubber surface and it will seal every time. A rubber plug from the hardware store for the intake manifold will work. Drill a 1/4" hole through it and insert a 1/4" barb into it. I use safety wire to secure the rubber plug into the intake and also grease it. It seals well. If your carb mounts with a rubber flange, then PVC connectors can be made that will tighten with the hose clamp. Here are some pictures.

[2stroker]

Thanks for all the info. I will give the leak down test a try. I think the cylinder might be warped. Will try bigger jets to see if that makes it run better once I fix the air leak.

[Bullfrog]

If you let us know a bit about your engine, exhaust system and your home elevation AND the jetting specifications in the carb you have, we'll be able to give you an educated guess as to whether your carb is close or wayeeeee off from the jetting which might be "normal" for your situation.

Engine cylinder type - iron Wombat, Combat Wombat, Super Combat, other
Exhaust system type - stock Wombat, Combat Wombat, other
Home (or riding area) elevation
Carb specs: Main jet, needle jet, needle (and clip position), slide cut-away (number stamped in bottom of slide), pilot jet, pilot air screw setting (number of turns "out" from closed position)

Ed
PS: I expect that you are going to find a significant leak (or two). When those leaks are resolved, things are going to be much better.

[2stroker]

cylinder - iron wombat (i don't know for sure) bored out to .080" over
exhaust - expansion chamber (on side), don't know what it came from or goes to
elevation - 26 ft, from my city's wikipedia
carb specs - I have a brand new 28mm Mikuni (NOS?) on the bike. I can't find specs on it anywhere. Mikuni just skips over from 26 to 30. I will have to update this once I tear into the carburetor, unless someone knows what the specs are for this carb (I haven't changed anything inside it)

intake - stock
air filter - slip on UNI filter
gas/pre mix - regular pump gas, mixed 20:1 with peak 2 stroke oil