<-=- Club Bevel Heaven -=->

Hi
Have just put on conti exhaust form the original one, on my 860GT. Now I have adjust carbs at idle to suit. However the front cylinder carby coughs slightly (every now and than-not excessively) when backing off the throttle? The front cylinder seems to run rich even with the old exhaust on?
Should I leave the needle set on the middle adjustment?

I have checked the inlet manifold gasket and carby clamp-OK

The exhaust gaskets are new and tight-double checked all OK there.

Any ideas? please.

Try raising the needle 1 step [drop the clip]. Or maybe a half step washer under...

Put old exhaust mufflers on still doing it (coughing) and running rich. Pulled front carby off and found main jet is 135 not 122. So I gather this is my problem?
Will put a order through for some more gear soon, Steve.

Wags wrote: ... Pulled front carby off and found main jet is 135 not 122. So I gather this is my problem?

Well, that would tend to make it run rich at full throttle, but not at idle when the main circuit isn't (shouldn't be) in play.

Sounds more like a partially blocked air drilling, or floats set too high ...

Ciao

Craig

Found rear carby had 130 jet in it?
Idle was fine only blows excessive fuel when revved. At night with bright lights in the shed you can see these clearly.
Hard accelation is good, just coughs when backing off, not a backfire.
Also when started and trying to warm it up and using a little of throttle it happens(coughing) a fair bit till it is fully warmed and idles fine.

I've only brought this bike 6weeks ago and been trying to get it running right since, it's got a freshly rebuilt engine . Maybe that's why they sold it?. However size 135 and 130 jets are a fair bit bigger than the specs mention 122 for a 860GT. 135 jets where used in 40mm carbs with the SS models which had bigger cams /contis/ low restriction air intake.

Well I have set of 122 jets and 125 coming this week. I'll put them in and test again. Hopfully all good. I'll post up result!

No Joy

Well, have fitted new correct size jets 122,needle and seats, atomisers AB265, needles. Just about everything except the slides. Matched up choke jets to 75.
Found idle jets missed matched as well 58 and 60. Have another 60 coming!

Adjusted float bowl levels. Front carb has newer style bowl while rear carb has old style bowl. Each respective carb has the correct jet holder to suit different bowls. Do the newer stye bowls have to be different float level? 17.5-18mm???

Bike runs hard and good under acceration, but pops and backfires on de-accerations. Also while warming bike up with a little throttle pops till warmed up and than idles beautfully.

Front cyclinder still running rich compared to rear. Went for a ride with a group, the other riders behind saying it blows no smoke whats so ever. But when returned home, right conti black around inner pipe.

I have brought a timming wheel to check both cylinders advance timing.

Ongoing saga! The bevel journey continues.

Re the popping and backfiring on deceleration: might be worth checking that the clamps on the header pipe - cross-over junction and cross-over exhaust junction are air tight.

Steve.

Wags,

Have make sure your slides are adjusted correctly and opening in sync ? worth checking if the carbs have been played with.

Cheers
Rick

apologies,

just foundyour next post, advising carbs have been now been synced,

Cheers
Rick

Before you get too deep into jetting changes make sure the valve adjustment is correct and the manifolds are sealing to the heads.
Too tight on the valves will give you some of the popping you describe and bear in mind the if you have the old elettro. ign. syst. it will pop and fart on the overrun.

Can report that problem was with carby's have pulled apart and cleaned , blow air through it, checked, checked and double checked sync again, put it all together again and BINGO

Timing was good, valve clearance, Inet Manifold gaskets good, exhaust clamps, Electronica ignition coils was all good. Sanity of myself is now all GOOD just a little frazzled.

No fouled plug no couching, farting, belching. One Happy bevel owner once again.

Thankyou for all your replies.