Low speed jerkyness

[skull-candy18]

Finally got my trx insured and taxed after fixing some little problems.
So I went out on my first ride and noticed that the bike is really jerky at low speeds, I'm not sure if this is how TRX's are supposed to feel but it feels like I'm pulling off in 2nd or 3rd gear. It requires a lot of careful clutch slipping to pull off smoothly. Also when riding at 30mph 2nd is the only comfortable gear, 3rd feels jerky likes its too high a gear.

I've only rode a few other bikes but I could ride at 30 in 4th or 5th on those. So my question is, is the trx really tall geared and jerky at low speeds or do I have an issue ? And if it is an issue where can I start looking ?

[fung]

OEM is 17/39 gearing which is quite tall.
For the open road, this is fine, but in town it is a little rough.
check the sprockets for hooking teeth also.

[Snod Blatter]

Third should be fine for 30MPH, I can trundle along in 4th at that speed with a 41 tooth rear sprocket.

Did the previous owner mention any "improvements" that might have happened to it?

[bubbaad]

Yes, have a look at the rear sprocket and if it has 39 teeth (factory) change it for a 42. Your chain will still fit and and the gearing will be much better for everyday use. Then fit a big bore exhaust, FCR's................................

[Kevtrx849]

Also check for chain tension and throttle free play. Both easy adjustments which can convert your bike from a jerky pig into a smooth assassin .

[Silver]

Agreed kev, You need all the slack in the chain and correct throttle cable adjustmernt. Makes a big difference. But it will always be a bit sensitive to throttle at low speeds.
Dave

[fung]

and if all else fails, do the TPS reset as per the manual/ threads on the forum.
cheers
fung

[Stu99]

Finally got my trx insured and taxed after fixing some little problems.
So I went out on my first ride and noticed that the bike is really jerky at low speeds, I'm not sure if this is how TRX's are supposed to feel but it feels like I'm pulling off in 2nd or 3rd gear. It requires a lot of careful clutch slipping to pull off smoothly. Also when riding at 30mph 2nd is the only comfortable gear, 3rd feels jerky likes its too high a gear.

I've only rode a few other bikes but I could ride at 30 in 4th or 5th on those. So my question is, is the trx really tall geared and jerky at low speeds or do I have an issue ? And if it is an issue where can I start looking ?

With stock gearing, you are correct 2nd @ 30 will feel ok and get you 3000rpm, 3rd @ 30 will get you about 2250rpm which will feel like rubbish. It is a twin after all. 3000 to 8000 rpm is its happy place. As suggested change to a larger rear sprocket and/or smaller front sprocket. 17/42 and 16/41 are both good choices.
Check out gearing commander: http://www.gearingcommander.com/
As mentioned also check chain tension, chain and sprocket wear, throttle cables etc and it wouldn't hurt to check your cush drive while you are at it.

[skull-candy18]

Thanks for all the help. I've cleaned, lubed and adjusted the chain as it was a little slack (about 33mm), its just over an inch of slack now now which is about 27mm so in the recommended amount. Couldn't find any tight spots per say and the seller said it was new so I beleive its all good.

Checked the throttle slack and there is none, as soon as I move the throttle the bolt on the side of the carb starts to move, this is how I set it on cars so I think it is correct.

So I think its a case of getting use to the high gearing and big twin set up. I will swap to a different rear sprocket at some point but this one looks new so I will use it for a bit longer, I think it was because I had a go on my Dads modern Bonneville I was expecting it to be like that due to both being big twins. Either way mines more fun to ride over 30mph

[Snod Blatter]

You want at least some slack in it otherwise every small movement you make will have the engine responding to it. The owners manual says 3-7mm though personally I go with around 2. But you at least want a bit!

[thch]

So I think its a case of getting use to the high gearing and big twin set up. I will swap to a different rear sprocket at some point but this one looks new so I will use it for a bit longer, I think it was because I had a go on my Dads modern Bonneville I was expecting it to be like that due to both being big twins. Either way mines more fun to ride over 30mph

Well, the reason the TRX acts this way, is the 270 degree crank - it's an inline 2 but feels like a V2. It is supposed to cough and splutter below 3K
The S10 has the 750 engine with a 180 degree crank - this is an entirely different matter - my S10 runs ever so smooth in 5th gear at 1500-2000 rpm
180 degree vs 270 degree - it's like 2 completely different engines!

-Thomas

[rogerc41]

Have you checked your cush drive rubbers in the back wheel at all?? If they are old, hardened, worn, etc it may lead to hashness in the drivetrain. Worth a check on an older machine.

[handsomejackuk]

can i fit a 42 tooth rear sprocket with standard chain length..?

[Snod Blatter]

can i fit a 42 tooth rear sprocket with standard chain length..?

Yes, I would guess it's good for up to 45 teeth, maybe 46.

[brenyw]

Low speed jerky is usually from the carbs.
The mixtures were never set up perfectly from factory, but they get even worse when the needles and emulsion tubes wear (pretty easy to fix).
If it's available, try an ethanol blend fuel (10% ethanol) which has the effect of leaning out the mixture.
If the bike runs smoother then it's probably worn needles/tubes.