Topic: cr29'ers drowning my engine so it wont start

[fr33man]

Hey Gang,
i have a problem with my cr29's - i bought them 2nd hand and having a few problems with them overflowing drowning my engine so that it wont start. what do i have to do to stop it from doing so? =)

im kind of a noob but trying to sort out and upgrade my mechanical skills - so your help is strongly appreciated =)

[POPS 911]

FLOATS STUCK IN OPEN ? MAIN JET TO BIG, IDLE JET TO BIG, pull the bowls and take a look to see if floats hanging move up and down. I have seen stock bikes with 145 and bigger jets and the same stock bikes calls for a 118 mains, someone thought they had a monster HP bike and went way to big on jets.......

[Retro Rocket]

If the carbs are "drowning" the engine I would dump the oil out before you screw everything up, fuel in the oil is a recipe for disaster. Is it a stock engine...? 

[turboguzzi]

well, if by your own admission your a noob, then question is why jump into more difficult to set CR29s?
that said, you could open the fuel for just a few seconds then close, so at least you can get it started without flooding.
but you certainly need to understand why it's flooding and fix it, you could try to check with carbs outside of bike and see why the floats/needles dont stop the flow

[fr33man]

Engine is stock, main is 120, float is moving and hight is good (14 mm) needles look clean on surface. Will look at idle soon

[turboguzzi]

so have to ask again: what's the point of putting CR29s on a stock motor? serious question. you'll get much better response and driveability with stock 28s, VM27, etc. and can sell those CRs (to me among others ) and save yourself a lot of grief from trying to set them up.  Just my 0.02$

[PeWe]

I do not know the CR carbs. Mikuni has a bottom plug in each float bowl that can be replaced by another plug with clear tube mounted. The tube bent upwards and will show the fuel level in carbs when fuel is switched on. 2-4mm under the float bowl gasket. This will show if they flow which they probably do. I attach a photo example from VM29 smoothbores with clear tube checking fuel level after adjustment.

Or if it is a CB750 tune the engine so you can use the carbs
Find a ported head and a moderate cam with not too much duration that need higher CR pistons. Or do the pistons too.

[Retro Rocket]

so have to ask again: what's the point of putting CR29s on a stock motor? serious question. you'll get much better response and driveability with stock 28s, VM27, etc. and can sell those CRs (to me among others ) and save yourself a lot of grief from trying to set them up.  Just my 0.02$

Beat me too it, there's absolutely no reason to run race carbs on a stock bike, makes no sense at all, all you'll end up with is worse fuel economy and a pain in the butt to tune properly. Put the stock carbs and airbox on and save yourself some grief....

[fr33man]

Dont want airbox.. better get head ported.. read in some post here that someone did a good job in Holland but still .. think its way too much to ship it to the states..

[calj737]

Even with a ported head, you are still "over-carb'ed". Save yourself heaps of time, frustration and money, and sell the 29s and install some well tuned stock carbs.

Perhaps set the 29s aside and wait for a built up HiPo motor to use them on. Porting alone won't be sufficient to create the vacuum pressure necessary for these pampers. They're specifically designed to produce fuel flow rates necessary for high lift, high duration, higher compression motors that require more fuel in upper rev bands than your stock motor generates.

Best of luck-

[turboguzzi]

+1
and airboxes add to driveability, even if they dont look so hip

[POPS 911]

To big for stock motor 29's/ 120 main ?  If CRs have groves on needle set it at the top groove and put in a smaller main jet 112-115 or two jets smaller than 120. I learned a lesson by going to big and it took a long time to get the right grove and main jet for drag racing = street riding would be a whole different testing of jets and mains, idle and needle height. A different exhaust is another try this try that on a dyno.

[PeWe]

Compare with Mikuni VM29. Mains 115, pilots 17.5 according to http://www.z1enterprises.com/Z1CarbGuide.aspx
I guess this is for a std engine? Simlar sizes might work in CR29 too?
Check the video here. CB750 with CR29, 115 mains: http://gnarlywrench.blogspot.se/2012/05/keihin-crs-on-1973-cb750.html

More CR experiences, it should work! Don't give up 
http://forums.sohc4.net/index.php?topic=40413.0

[calj737]

If only Democracy ruled others people's choices...

[754]

Go backwards, try stock see if it runs, then jet the CRs near baseline jetting before screwing up worse.