Will this work?

[Sal Paradise]

I have this little old Japanese bike and I am cafeing it. I need to get a 2 into 1 exhaust on it but there is none available. I ordered a compatible system for another bike but the flanges are different. I cut off the flange and about 2" of the stock header pipe... I can hammer in the stub of the stock header until the flange is all the way in. Its tight. I can then drill and put a stainless screw there if I am worried about it moving at all. That's a new exhaust gasket to seal that joint. Its invisible on the bike, I just mocked it up. But will it work? Anyone ever do anything like this? Does it look workable? Or shouldl I send this system back and search on?

Look at this -

here is the bike...

 

[Craigore]

looks good to me, I'd try it. as long as you can actually torque the pipe down at the flange of the new exhaust i don't see any issues at all.

 

[Sal Paradise]

Ahh you are right it probabyl would have worked but I just cut the ends off and welded the original ends on. Better.

 

[Kirkus51]

Ahhh. Welding! A talent few of us have.

 

[dschief]

Ahhh. Welding! A talent few of us have.

Yes, but most of us know someone that can. I have a whole crew of welders at my disposal, and one of them actually knows a lot about bikes. Good friends to have.:rockon:

 

[Sal Paradise]

doing any type of " custom" or home made exhaust you gotta weld. I can weld but I actually brought it to my buddy' shop and so he welded it. Here is the pocket rocket back from the shop.

 

[dschief]

That looks pretty damn cool!

 

[strokerlmt]

I like the under the engine bend....cool
LMT

 

[Sal Paradise]

So, to get that great Cafe look - I ripped the airbox out of my little Zuki. It also got a 2 into 1 exhaust at the same time. Ok so now running pods , etc. and it runs like absolute crap.

I have jetted the thing all the way from 117 ( Mikuni ) to 132.5 with little or no improvement. The carbs are CV Mikunis from 1981 , clean, operating normal - I checked the slides and floats. Good.

I did a few plug chops Plugs are showing lean. Bike starts up fine but breaks up above 5k rpms. I don't think its making as much power as it used to either. Previously the bike ran fantastic. I suspect at this point that the slides don't go up like they used to because there isn't enough vacum. The internet is rife with reports of pods and CV carbs that don't work right.


I am about to go back to the original airbox and jets if I can't get anywhere. Really wanted the pod look but if I can't make it work what's the use? I am getting really sick of pulling these carbs and I have a ton of other work to do. Anyone podded these old CV Mikunis? Should I drill the slides or just put the stock airbox back on?

 

[dschief]

My experience is with Mikuni VM carbs, which are direct pull slides. On the VM's, which are on 2 strokes, if you remove the airbox and use pods you will end up around a 200 +/- main jet size after starting at a 120, which is what it sounds like you may need to do. You have added a lot of airflow to that engine, it needs more gas!

 

[strokerlmt]

doing any type of " custom" or home made exhaust you gotta weld. I can weld but I actually brought it to my buddy' shop and so he welded it. Here is the pocket rocket back from the shop.

Sal I can hear the battery saying, "its soooo colddd out here pls put me under the seat ;-)) ".
LMT

 

[Sal Paradise]

Yeah, the battery is going up under the seat, maybe a small Lithium one. That should clear up the awful wires.

But I need to get this bike " On the Road" before taking that step.

 

[Sal Paradise]

again, hoping someone has knowledge

So, to get that great Cafe look - I ripped the airbox out of my little Zuki. It also got a 2 into 1 exhaust at the same time. Ok so now running pods , etc. and it runs like absolute crap.

I have jetted the thing all the way from 117 ( Mikuni ) to 132.5 with little or no improvement. The carbs are CV Mikunis from 1981 , clean, operating normal - I checked the slides and floats. Good.

I did a few plug chops Plugs are showing lean. Bike starts up fine but breaks up above 5k rpms. I don't think its making as much power as it used to either. Previously the bike ran fantastic. I suspect at this point that the slides don't go up like they used to because there isn't enough vacum. The internet is rife with reports of pods and CV carbs that don't work right.


I am about to go back to the original airbox and jets if I can't get anywhere. Really wanted the pod look but if I can't make it work what's the use? I am getting really sick of pulling these carbs and I have a ton of other work to do. Anyone podded these old CV Mikunis? Should I drill the slides or just put the stock airbox back on?

 

[sweatmachine]

Did you only change the mains?

 

[ivar]

not familiar with those CV mikunis, but I assume they are similar to the keigin CVK's on the bonnies? If so, I'd suggest putting a couple shims on the needles just to see how it responds

 

[Sal Paradise]

Jeff , NO - however I will probably change the pilots next time. I turned out the air screws of course. Its starts and idles fine. Its the WOT at 5,000 rpms that is messed up.

Ivar, the mikunis do not appear to have needles that you can shim. They have a snap ring that seats them and no apparent way to change the height.

 

[dschief]

Are you sure you can't reposition the c-clip on the needle? That's how it works on the VM carbs. Not sure, just asking. I still think you need to go bigger yet on the mains.

 

[Sal Paradise]

I will bump it up again to a 140 and follow it up to a 150, after that I think its too much.

I have read about about the lack of vacuum on the front ( airbox side) port of the carb causing them to not raise the needle

 

[B06Tang]

This would be a good time to dabble with some painting? Are you going to give that a swirl too?

 

[dschief]

Yeah, not sure about the vacuum effect. Couldn't hurt to try though.
If you go up and it bogs really bad, then you'll know you are too rich. Doing a plug chop with a main that's too big, the plug(s) should be wet or gas fouled.