Suzuki GT250 tuning

[chrisc]

Anyone on here a racer from way back that can share some tuning experience with the X7 GT250 Suzuki?

I picked one up over the weekend which needs more than a bit of a attention. Plan is to get it going properly on the road for a quick hoon around.

I've never seen this type of reed valve assembly before, clearly i'm showing my age here.



If you have parts lurking around, particularly the older spoked wheels, send me a message!

Chris

[Grumph]

The X7 can be made to go quite well. Limits are usually cooling - finning is pretty scanty....
Like the LC, the head is one piece so doing the squish is not easy.
Bits are readily available, I reco'd one for a guy here a couple of years back. Pistons, rings,seals,rod kits, mains all ex UK.
From memory, not much change from 2K.

Talk to F5Dave about case reeds, he's the believer....

[husaberg]

Anyone on here a racer from way back that can share some tuning experience with the X7 GT250 Suzuki?

I picked one up over the weekend which needs more than a bit of a attention. Plan is to get it going properly on the road for a quick hoon around.

I've never seen this type of reed valve assembly before, clearly i'm showing my age here.



If you have parts lurking around, particularly the older spoked wheels, send me a message!

Chris

Pretty sure they were the same set up as the Rg50 and quite a few others incl the tf125 re the reeds.
Side note I don't think I ever seen one that was not red.

[Grumph]

Pretty sure they were the same set up as the Rg50 and quite a few others incl the tf125 re the reeds.
Side note I don't think I ever seen one that was not red.

Pretty sure there's a blue one comes out with CAMS - but yes, all others I've seen were red.

[husaberg]

Pretty sure there's a blue one comes out with CAMS - but yes, all others I've seen were red.

They probably would have sold alright if the LC had never came out.
Does the RG250 have the same flat reed set up or different? Never seen one apart.

[chrisc]

The X7 can be made to go quite well. Limits are usually cooling - finning is pretty scanty....
Like the LC, the head is one piece so doing the squish is not easy.
Bits are readily available, I reco'd one for a guy here a couple of years back. Pistons, rings,seals,rod kits, mains all ex UK.
From memory, not much change from 2K.

Talk to F5Dave about case reeds, he's the believer....

Yeah machining the head doesn't look like much fun.

I'm pretty keen to get some modern single ring pistons in there. 14mm pin sucks though.

[F5 Dave]

Yeah all Suzuki's had that setup including the 4 strokes. OK maybe not but RMs, PEs, TS, RGs of all sizes. It's a bit of a shitty system. The latter the model the flatter the reedblock.

My X7 had TS125 pistons which takes to 275. Heads cut in two and some porting and skimming.
The cranks like most Suzuki's is barely adequate.

You'd want to rebuild crank from the start and try find some Yam parts to fit. Opens up piston options.

GS550 caliper dramatically improved the brake. GS550 shocks discarded from my old 550 were longer and stiffer and helped ground clearance, steering and despite being rooted were better than std.

Think I saw the old motorcycle mechanics article on the web recently.

Mine was Blue, there was White and Red too. X5s seemed to be black or yellow but they are a bit different. A mate has just done one.

[T.W.R]

Think I saw the old motorcycle mechanics article on the web recently.

.

Have got the 3 issues from May 1980 - July 1980 , basically they took a RD250E & a X7 ( with 8800 miles on it) and tweeked them. The X7 went from measured 17.9bhp @ the wheel to a max of 30.5bhp ; used larger carbs pod filters micron pipes etc and lot fiddling and testing. Will scan the series when I get a bit of time

[husaberg]

Have got the 3 issues from May 1980 - July 1980 , basically they took a RD250E & a X7 ( with 8800 miles on it) and tweeked them. The X7 went from measured 17.9bhp @ the wheel to a max of 30.5bhp ; used larger carbs pod filters micron pipes etc and lot fiddling and testing. Will scan the series when I get a bit of time

I have the one where they went through the design process I will post them as well then.

[chrisc]

Thanks for that lads. Mine is currently house paint blue but was red and will again be red soon enough.

[TZ350]

Anyone on here a racer from way back that can share some tuning experience with the X7 GT250 Suzuki?

Will the next model water cooled RG250 cylinders fit??? if so give me a PM.

[TZ350]

Yeah machining the head doesn't look like much fun.

A few $$$$ and Sketchy with his CNC machine is an option.

[Grumph]

A few $$$$ and Sketchy with his CNC machine is an option.

If you split the head to machine squish - a good option IMO - take the time to dowel head and barrel as there's no positive location on the damm things.

[chrisc]

Will the next model water cooled RG250 cylinders fit??? if so give me a PM.

Now there's a thought! I'm keen to keep it air cooled though, it won't be stressed that much on the street.
Will give you a call anyway Rob

[husaberg]

Try here
http://www.suzuki-gt.co.uk/Reference...20Page%202.htm
I had already scanned this one when I found this page
I have also converted the 250 shot out.
There is a pretty decent tuning article based on the very quick look I had.

Also in Bells book he goes through the Power Reed system including what happens if you take it to far.