Timing GT 250 A Model

[triplesmart]

Hi There,

Is there any differences in Timing of the GT250A compare to the Ram Air Models?
If yes? What?

THX

Dirk

[jabcb]

The A/B models have different timing than the earlier models.

Early GT250As have two timing marks while the later As & the Bs only have one.
See service bulletin GT-30: Also see GT-32 for other differences:
http://www.ozebook.com/compendium/techb ... 027-33.pdf

They also made changes partway thru the GT250A production run. See GT-35:
http://www.ozebook.com/compendium/techb ... 034-39.pdf

Additional specs are in Specification-8:
http://www.ozebook.com/compendium/techb ... %206-9.pdf

[Craig380]

This document is also useful: http://www.suzukigtriders.co.uk/technic ... 0A%20M.pdf

The timing for the 250A is 2.05mm BTDC, compared with 2.93mm BTDC for the 250M, but Suzuki never changed the timing marks ... so use a dial gauge!

[jabcb]

The timing for the 250A is 2.05mm BTDC, compared with 2.93mm BTDC for the 250M, but Suzuki never changed the timing marks ... so use a dial gauge!

Are you sure?

Service Bulletin GT-30 says that easy GT250As have two timing marks & later versions have cranks with relocated rotor keyway.

[Craig380]

The ignition timing specs are correct ... as for the timing marks, I remember reading that Suzi didn't change the timing marks from the M to A model. I've only ever worked on a Ramair M model, however.

[jabcb]

My guess is that the service bulletins are right.

It says that if you replace the rotor on an early GT250A then you have to add the 2nd timing marks yourself.
They did change the crank part numbers but the parts manual doesn't indicate what the change was.

But if buy a GT250, it might not have the original crank and/or rotor.
So even if Suzuki did exactly what they said in the service bulletin, your bike might be different.

So its good advise to check with a dial indicator to make sure the timing marks on your bike are good.

[tz375]

This is my interpretation:

The last GT250 was very different to earlier models in that it had extra transfer ports and a different crank and crankcases. The same rotor was used but the later model had its timing changed from 24 degrees on early models to 20 degrees on the last one. On some late models, they simply added an additional mark to the rotor and then they changed to a crank by machining the keyway in a different position. That allowed them to go back to the same rotor that they had used before the change.

So if you have an earlier bike, any rotor will work but if you have fitted a 20-24 rotor, use the normal timing mark.

If you have a later motor, check with a dial gauge to be sure. Pre 76 are 24 degrees and 76 is 20 degrees.

[jabcb]

Last year I bought an early GT250A that a shop had rebuilt with new crank seals.
Runs fine but is hard to start cold. Hadn't looked into it yet.

Maybe the shop used the wrong timing marks.

Bike has pod filters. So I'm thinking the other possibility is stock carb jetting.