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hi all, took my h2 for a blast earlier and when its below 4000ish rpm and about 1/4 throttle it sort of boggs down and stumbles but if i crack the throttle open it picks up again and revs right through no problem.ive stripped the carbs and cleaned them thoroughly, set the mixture screws 2/14 turns out and balanced all the carbs with a morgan carbtune and its still the same. the revs also hang slightly at 2000 only for a second or so then drop to about 1500 and idles fine, after reading on here i think the hanging revs is down to sucking air in from somewhere possibly carb to head rubbers so ill check them tomorow, any ideas on the bogging/stumbling?

I would say it might be bogging because of the air leak. Spray some carb cleaner round the carb inlet rubbers and if the revs change then you may well have a leak, also check the clamps are done up tight and the airbox sits properly on the top of the carbs.

ive just stripped the carbs again, took the rubber between carbs and head off and they looked fine but i cleaned them and put some gasket sealant between them and the head, set the mixture screws at 2 turns out and refitted carbs. took for a ride for a few miles to get up to temp but its still bogging down at part throttle between 3500-4000 rpm, the revs dont seem to hang any more though so thats cured. ive got a set of new plugs on order ( although the ones in now are fairly new and are all a nice brown color), ill stick them in when they arrive and see how it goes and let you know the results.

Is it a standard bike ?

Is it not just a trait of the OEM exhaust system being so restrictive coupled with the airfilter ?

Check your carb's internals are also all original and haven't been tuned for a free flowing system and when bike was sold it was taken off, or vice versa.

its a standard bike except for a scorpion race can, all carb internals look standard. i dont think its a trait of the bike, it sort of stumbles and hesitates between 3500- 4000 rpm on part throttle but all i have to do is twist the throttle to say half way and itll sort itself out and rev right through fine

The race can is probably responsible for upsetting the fuelling and introducing a big flat spot. Ideally you need to get it on a dyno to check the A/F.

Always love how they call slip-on & bolt-on cans " Race "

Who the hell goes racing with a standrad exhaust system on

Dynojet stage one kit should sort it out - follow the instructions, all the dyno work has been done !

MM!

i only call it a race can as oposed to slip on or bolt on because it has not for road use stamped on it. i might give the dynojet kit a go as you say all the dyno work has been done, i have the std can too so might stick that back on first and see how it goes