1198 or 1229

[jstewart]

I have decided to go ahead and build the motor on my 85 GS 1150. I am in a quandary over whether to go 1198 or 1229cc's at 10.25/1 compression. I was originally going to leave it stock displacement but after finding 2 cylinders with 135 & 130 cold cranking comp. I want to take this motor down completely. The bike came to me with a set of Web 167 grind cams, a stock clutch hub, stock exhaust & carbs. So the plan now is to pull it down & split the cases to inspect the bottom end and transmission. The mods I have decided on as a first step are a beefed up clutch hub with a new clutch, manual cam chain tensioner, undercut the transmission, re-use the Web 167 cams, use a set of 38mm GSXR 750 CV carbs and pod filters, street port the head with stock valves, run the stock exhaust system for now until I can find a 4/1 exhaust in good condition. I know the Web 167's are pretty mild and may try a set of Web 640's later if I can find a good header. For now I think I will just stick with the 167's and the stock exhaust because of expense.

Is there any downside in reliability from running a 1229 over a 1198 at 10.25/1 comp. in the stock cylinder liners? I build two 1198's without any trouble 28 years ago but no experience with 1229's. Not sure how much cylinder wall is left with the 3mm overbore of a 1229. This will be strictly a street performance bike not used for a drag bike.

 

[blowerbike]

i like 1198's because they leave you more cyl. thickness.
and i have to add this...
there are dozens..many dozens of 1150's with work done to them.
i would leave it stock...yes just my opinion but the last 1150 i had i put it back 100% stock and enjoyed every minute of it.
i have had low 10 second 1150's(10.30 flat) so i have been there...done that..and did it with stock pistons and head just cams and RS 36 miks..
your bike...your choice but i see your good deal going south by spending a couple grand or more on it.
there you have it...pm me if you ever need any advice because i believe i am at the top of the list on this site for back ground on these bikes..:hypnotysed:

 

[Nessism]

130/135 psi cold is respectable. What's the compression on the other cylinders?

 

[ArttuH]

I have a stock 1150 block bored to 1229cc on my turbo GS. It has been in use for few years now. No problems with oil consumption and leak down and compression figures are still good. So based on this I would say that liner wall thickness isn't a problem yet. As far as I know the 1150 block can be bored to 1260cc but then you might be asking for trouble.

 

[Guest]

No problems with 1229s.

 

[rapidray]

I am a "Bigger is better!" kind of person myself. But I think 1400ccs is good for the street! It is a sickness. Hi, my name is Ray & I am a horsepowerholic.
Ray.

 

[jstewart]

130/135 psi cold is respectable. What's the compression on the other cylinders?

160/165, this is cold cranking compression.

 

[rapidray]

That is good compression. What is the issue?
Ray.

 

[jstewart]

That is good compression. What is the issue?
Ray.

(1)--130, (2)--165, (3)--135, (4)--160 This much deviation is good???????????

Honestly I don't know what the problem is yet Ray, if it is one, because my garage is unheated and being a wussy I have not pulled the head & cylinders in the cold. It was 50 degrees when I did the compression test and after squirting a small amount of oil in the cylinders and cranking the bike I repeated the cold comp. test, same result. The temp dropped well below freezing the next day and I have not been out there to work since. Been concentrating on rehabbing parts (rebuilding and painting brake calipers, painting swing arm, lining gas tank) I removed that can be done inside. A leak down would be good but I don't have one anymore.