2002 Suzuki GSX750f acceleration problem

[jaffa90]

The exhaust is original,22 year old exhaust, is it breathing and nothing collapse inside as in a rattle?

[A100man]

[jeffyjeff]

To my knowledge, carburetor main jet operation is dependent on air flow, not engine speed. At no load (transmission in neutral and throttle pinned), rpms should bounce off the rev limiter without engaging the main jets. Symptom suggests a timing issue. Maybe the cam timing retarded... might be worth a check and won't cost anything.
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History shows again and again how nature points out the folly of men - BOC

[Nobby the Bastard]

Cam timing showing up at 7k revs on full load? Are you fucking kiddding?
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[jeffyjeff]

[A100man]

[jeffyjeff]

[A100man]

[Pete.]

I've seen someone battling with this kind of issue on a drag bike. Vibration at a certain revs was causing a poor connection in an electrical connector. Only happened at the one RPM just happened to be a resonant frequency for that part.

Put a volt meter on the coil power lead and see what it does when you hit the RPM where your trouble starts.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Landyman]

Hello Again Everyone.
This is what to many of you will be an obvious question but, I want your answer.
I am replacing the O-Rings in the carb Manifold boots, do I bolt them together with dry surfaces or would you recommend a little smear of Hylomar?
Kind Regards

[Nobby the Bastard]

Pretty sure most instant gasket types don't play nicely with petrol.
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[A100man]

[Nobby the Bastard]

Apparently Hylomar Universal Blue is fuel resistant...
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[stinkwheel]

I generally don't use anything more than a smear of oil or grease to help the o-ring squish down evenly. They should seal unless the mating surface is damaged. I put a tiny wipe of red rubber grease on carb rubbers to assist with fitting.

I use permabond A136 on gasketed manifolds.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Landyman]

Good Morning and Thank You Again.
You are right about Hylomar Blue, it is resistant to oil, petrol and a host of other stuff plus it is none setting and can be applied under water but, I've never used it on a 'dry joint'where it's two machined surfaces and a Nitril O-Ring. I think I may just stick with a grease smear.
The big build should be finished this weekend, subject to eBay deliveries, after which it's fingers crossed that the work and new parts pay off.
Kind Regards

[that_impulse_guy]

hylomar never dries.
never.
so if it gets sucked in, it'll be around forever....maybe it'll block a jet...maybe a oil feed.
maybe it just goes and sits in the oil filter.
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Gone: Yamaha DT50lc, Suzuki DR500, Suzuki A100, Kawasaki z250ltd, RD350YPVS, Suzuki DR Big, Kawasaki AR125, Kawasaki KMX200, Suzuki GS1000S, Katana 1100, GS550M, Suzuki RGV250
Now: Suzuki GSX400X, Suzuki RF900R, NS400R

[Pete.]

Bike engines will rev to the moon if you squirt petrol into the intakes with no carbs fitted. Spray some go juice down its throat with the carbs off and if it still falls over at 5k your problem is not fuelling.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Landyman]

And Finally.
Just to keep you up to speed, the problem has been sorted. The whole issue has taken time, patience, a little money and repeated strip, fettle, rebuild and test, until it was fixed.
Jobs done finalised with removing the inlet manifold boots, removing the knackered O-Rings, cleaning each boot till they were perfect before conditioning with red rubber grease and fitting new O-Rings. Replacing the main jets with new, replacing the pilot air jets with new, re-setting the floats with the aid of a digital vernia and polishing all the surfaces.
Success! Starts, ticks over, revs and runs like a Swiss watch.
Thank You Everybody for your advice, ideas, guidance and support, it has all been helpful.
Kind Regards.

[A100man]

[jeffyjeff]

Manifold boots and leaking o-rings suggest the mixture was running lean, in my estimation.
____________________
History shows again and again how nature points out the folly of men - BOC