81 Gs1100e

[ghainjr1]

Okay guys and gals, I need your help! Please!!! I took my cylinders to a local shop to get honed and checked. Honing was fine and they told me that they are standard bore. Order new piston pins and rings and they dont fit. I measured the pistons and I'm looking at 74.5 mm. I have no idea what brand these are there are no markings except the C on top. Can someone give me a little insight? Thanks Greg

http://s53.photobucket.com/albums/g72/ghainjr1/

[Steve]

You only say "they don't fit". In what way? Are the pins too long, too short, too fat, too skinny?

Don't know about your particular engine, but I have seen some that use interference-fit piston pins. The way to install them is to place the pistons in an oven (150-200 degrees) for an hour or so, and put the pins in the freezer. Assemble quickly, the parts will return to their normal sizes and be locked into place rather quickly.


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[ghainjr1]

I'm sorry the pins fit in just fine. The stock ones are shorter.

[ghainjr1]

The pins I took out are 63mm.

[NICK!]

Those appear to be low compression pistons, what is the history of this bike? We would call these "blower pistons" and they would be meant for a supercharged or turbo engine. We also use to use them for large dispacement street race engines so they could survive on pump gas and not detonate but since your engine is stock displacement it is a mystery. There were a lot of piston kit manufacturers decades ago, almost all are gone now except for Wiseco. Were the wrist pins retained with a teflon button or a circlip or spiral lock? Are your current wrist pins marked up (worn) and how was your compression? You might be best off using the old stuff if its ok.

[NICK!]

I just looked at Wiseco's catalog, their small kit for that engine is 1134cc which they claim is 74mm bore and 2mm oversize. Looks like the cylinder is overbored. Are your wrist pins 18mm in diameter?

[ghainjr1]

A circlip on one side and spiral lock on the other. Piston pins are probably usable, but was trying to replace what I could with it apart! I'm screwed for rings though, they went in the trash a couple months ago. I dont know anything about the history of this thing. Won it on Ebay a few years back and trying to figure it out ever since. The Photobucket pics also show my basket that I haven't been able to get any info on either. Thanks

[ghainjr1]

Yes pins are 18mm by 62.8mm

[NICK!]

Well, since there is little chance of finding new rings for these, you've got two options that I can see.


Since your cylinders are 74.5mm now you could mail the cylinder to Wiseco and get a 1166cc (75mm) kit put in (big bucks) but for a daily driver I would avoid a kit. At 10.25 compression getting caught in traffic could be bad for the engine.

Here's the other possibility, get another cylinder and pistons/rings with pins from a junk yard (like Willie's in Alabama) or maybe this guy, I stumbled across this looking for pictures of stock pistons. http://www.dynoman.net/used/index.html#pistons

I am certain those are low compression pistons because of the totally flat top and shallow valve relief but I'm going by memory, I'm certain the stock Suzuki GS1100 pistons had some features (dome) and deeper valve relief that that BUT I could be wrong seeing as I haven held a stock piston in my hands in almost twenty years. If you see dynoman's pistons and cylinder at the link above its hard to tell what the features of the dome are but I do see the raised circle in the center that I do remember.

[NICK!]

I looked at your clutch basket, man o man is that one herky basket! Sir, I'm going to go out a limb and say you've got an old funny bike motor there, this super strong basket (I've seen maybe a hundred reworked welded baskets in my life but never one taken to this extreme) plus what I see as low compression turbo pistons might lead me to believe that funny bike was the past life of this engine. Is the head ported? Do I see a spur gear on that basket? A spur gear is a straight cut gear and is stronger than a stock helical gear but they make a whineing noise which is why stock bikes don't use them. Are your con rods aftermarket?

[ghainjr1]

Dynomans says that those are stock pistons and trying to see through the carbon they look like mine. But mine cant be stock of course because of the size.

[ghainjr1]

Sorry I just saw the flat top,I didnt see that they were tapered on the sides.

[NICK!]

I just calculated your displacement, your engine is ~1149.6 cc's. This is a new one on me, never heard of an 1150 kit for the 1100 motor. I worked in Suzuki dealerships from 1983 to 1997, it is possible this was a short lived kit from before my time OR they are custom pistons which happened more often than you might think. Check Russ Collins (he only does fuel injectors now but I'm sure he'd talk to you on the phone) as I would think him the likely suspect. Doubt they are Yosh as they never got involved in drag racing. There was Arias and Jahn's and I have no idea if either of those companies are still around. Wiseco was always the piston company everybody used even back in my day.

[NICK!]

Sorry I just saw the flat top,I didnt see that they were tapered on the sides.

You may be right, as I said I'm recalling what the dome of a stock 1100 piston looked like from long ago, they indeed may have looked similar to your piston. I might be recalling the 10.25 to 1 street kit pistons.

Just went to the cellar and looked through some of my tools and parts, looks like the only 1100 pistons I have left are an 1133 kit that is drag compression, like 13.5 to 1 or something crazy.

[ghainjr1]

No the basket is not straight cut. What I have is a big mess right now and dont know how I'm going to fix it! A $500-$1000 Wiseco kit is not going to be in the budget anytime soon!