Big Bore....... anyone?

Howdy All,
I am thinking of getting myself a 1216 piston kit for christmas. It seems a fairly straight forward mod - get oversized pistons, rebore cylinders, rejet carbies, cruise into the sunset. How hard can it be? If the funds stretch far enough I'll look at a new slingshot 750 cam as well ($290, Holeshot). Neither mod requires any head or valve work.
There are a few questions that come to mind straight away:
*Any local suppliers?
*Compression ratios, 11:1 or 13:1?
*Longevity (only 30k on it now)?
*Fuel economy (not that it's such a worry, but I got 4.49l/100km on a recent trip to Nowra @~115km/h)?
*Jetting (stage 1 in now)?
*Recommended machining shops?
*Should I look at standard bore high compression pistons and a cam?
I'm keen, most of all, to get more torque out of it, but of course a couple of extra horses are always welcome Has anyone travelled this road before? Does anyone have a piston kit, or a cam sitting in the shed that never quite made it into the bike?
Any tips or suggestions are most welcome.

Tony.

Not quite ,but .I bought some oversize pistons (weisco) for a GS1000 i had .I took the barrels to a machine shop to get them honed
.I went to pick them up and he said "done in 5 mins " .After a short walk i retured to find he had dropped the barrels and smashed the bottom
of the sleaves .

Personally I’d go for a head job and cams.
The Bandit already has enough torque.
Obviously higher compression and cam will move the power up the tach a bit so a gearing change could be on the cards to keep it all in the sweet spot. Something in the order of 12:1 would be interesting and should only need a jet kit to keep up.

Hi Chris,
I should have put that I was just going for an intake cam. Both cams would give me a "totally nuts" top end and not much elsewhere (edit: should say less elsewhere). Just the intake alone won't affect the midrange from what I have read.

"Personally I’d go for a head job and cams."
I can' find any info on how far I can shave the head without banging a valve into a piston. A decent machine shop could tell me that, though. If I shave the head, then I have to go through valve timing, not a biggie, but something else to potentially go wrong, but then I don't have to take the block off. Other head work like polishing, etc, will just enhance maximum flow, i.e. top end.

I don't use the top end now, so I can't see me using it in the future. Then again if it scares and excites me at the same time.....or....maybe I should quit now, and buy a CT110. Seriously though, it's a really wonderful (even sporty) tourer. I'm not sure what else I can do to sweeten up the bottom and mid range. Maybe look for a tungsten flywheel and timing block?

Tony.

P.S. Sorry for selectively quoting your post.




I'm not sorry really.

Why not just turbo it?? It's been done before and will give you awesome mid range

One of the guys on PSB did it to a GSXR1100 I believe and it just smokes the tyres in top gear doing a roll on power skid how good would that be. Your fuel consumption will suck though.

Having had turbo charged vehicles I can just imagine a turbo charged bike would be fantastic fun

rolls wrote:Hi Chris,
I should have put that I was just going for an intake cam. Both cams would give me a "totally nuts" top end and not much elsewhere (edit: should say less elsewhere). Just the intake alone won't affect the midrange from what I have read.

"Personally I’d go for a head job and cams."
I can' find any info on how far I can shave the head without banging a valve into a piston. A decent machine shop could tell me that, though. If I shave the head, then I have to go through valve timing, not a biggie, but something else to potentially go wrong, but then I don't have to take the block off. Other head work like polishing, etc, will just enhance maximum flow, i.e. top end.

I don't use the top end now, so I can't see me using it in the future. Then again if it scares and excites me at the same time.....or....maybe I should quit now, and buy a CT110. Seriously though, it's a really wonderful (even sporty) tourer. I'm not sure what else I can do to sweeten up the bottom and mid range. Maybe look for a tungsten flywheel and timing block?

Tony.

P.S. Sorry for selectively quoting your post.




I'm not sorry really.

Tony

Ok why not just start with a cam job?
I was working on a head shave to raise the comp a smidge. Any engine work will be a compromise. Better in one area sacrifice in another.
The 1250 (&1200) lacks mumbo for the capacity IMHO and if I was to play around with mine I'd be doing head work before a rebore. Kawa and Yam must be laughing at our 98hp out of a 1200/1250. The options would be different if the bores were worn but thats not the case for you. Its only run in lol. I'm glad the decision isnt mine because I may even look at another bike.

Up to you mate. Oh and "quote away"

After looking at cost versus output, the bigbore idea is about the worst thing I could do on the bike. I'd gain about 5hp and a little more torque for over $1200 in parts, machining, gaskets, etc.

I've decided to go for a stage 2 jet kit, Holeshot complete exhaust and an '89 GSXR750 inlet cam. 25+hp and 20ft-lb torque increase for the same money. I found a second hand cam in Canberra in good nick for $100. I was going to mill the head as well but increasing compression will only give more hp and not torque, and torque was what I was after, besides an already extra 25 ponies will do me plenty.

Thanks for all your input. Maybe I'll look at bigger pistons next year?

Tony.

Dunno if I agree with you there, more compression = more cylinder pressure which is directly related to torque, and since it doesn't involve fuel, economy should not suffer and may even improve.

You could also check and see if Cometic (or similar) offer a high comp thinner head gasket. You may need to get some variable cam wheels so you can return to the correct timing as the thinner gasket will retard the valve timing a little, but if you are going slingshot inlet cam, then you may need to degree the cams anyway.

I thought the theory went more compression = more resistance for the piston on the up stroke robbing energy and while giving more bang on the down stroke, the power and torque being sent higher up the rev range.

I agree I should get a couple of variable sprockets.

Tony.

Hi Tony,

I can't see the relationship with RPM, AFAIK compression is a free kick...right up till you run into detonation(!). Maybe a post on Max-Zuke might give some answers...there are some idjots out there but there are also some very knowledgeable people, particularly when it comes to oil cooled Bandits. They can probably give you an idea of where the best bang for the buck is.

Cheers Peter

Thanks Peter,

I haven't seen that site before. I have the option of taking the whole GSXR head and using that with the bandit exhaust cam, but I'm not sure how much mucking around with carbie placement will be as the 750 dot head angles the carbies up steeper than the bandit. I don't want to have to run pod filters or jack the tank up either. Maybe I'll get some answers there.



Tony.

Go and ask them http://www.maximum-suzuki.com/forums/index.php

You will get some interesting and occasionally very useful info,

Cheers,

I've finished puting on a full Holeshot exhaust system, GSXR750 intake cam and stage 2 jet kit. The power delivery is beautiful, just what I was looking for and then some. There is just so much more smooth power and torque in the low and midrange, but after about 6500 it just hauls! I think my forearms have stretched about two inches just from a week of test rides.

I was looking to just buy a set of headers (Delkevic, AU$375 delivered), but the Holeshot headers are stepped, that is there is a smaller diameter pipe for about 6 inches from the head, and then a larger diameter pipe into a 4-1 collector. The stepped section is to keep the gas velocity high coming out of the head to keep the lower power range strong, something the Delkevic didn't have. If I didn't have the cam to put in I would have gone for the Delkevic headers, but I was keen to keep as much bottom and mid range as possible.

Unless you already have a Holeshot can you can't buy the headers so I bought a full system. For the can I chose a 17" comp (other being street) with black powdercoat finish. The sound is deep and crisp, and above 3000 quite loud. I actually prefer the sound of the Delkevic can I had on originally. If you want to buy anything from Dale Walker at Holeshot you have to pay with paypal, and YOU have to pay the paypal fees because we Aussies can't be trusted with credit cards. He does back up his products with fantastic after sales service.

I'll post some pics soon.

Yeah, all the good headers do that. I think its to do with the speed of sound (and other pressure waves) which is directly proportional to the gas temperature, as the gas cools it wants to slow down, and so then needs more area so it does not choke. At least, I think that's how it works. Looking forward to them pics.

ΔΔΔ Now I have a headache!

Im just happy ive got a brand new bike! Maybe im boring

oh shit look at the entry for speed of sound in wikipedia
"The speed of sound in an ideal gas is independent of frequency, but it weakly depends on frequency for all real physical situations. It is a function of the square root of temperature, but is nearly independent of pressure or density for a given gas. "

OH, QED

Actually to quote 2WA, Id go for the head job personally

Hey Rolls here's that 1216 kit you wanted

2nd hand 1216 kit

Thanks Dekenai, but I'm stuck. I can't log into the site. It wouldn't accept my password for some reason so I got it to send a new password, but it's gone to my work account which I won't see untill the end of January. I can't create another account because it won't accept hotmail or gmail email accounts, and there is no email account I can use with the wireless net provider. F^%$ing computers!

Can I ask - is it in Australia? JE or Wiseco? How much do they want?

Cheers,
Tony.

Hi Tony, "So financial reality slapped me upside the head recently and my dreams of rebuilding my motor as a 1216 just won't be happening for the foreseeable future. I'm selling off some of the parts I've procured, the first being this 88' gixxer 1100 jug w/ Wiseco pistons. The pistons have J99J4 and 4617PS XG stamped on them; I can't seem to find a description on Wiseco's website but I think they are ~12:1 compression with a stock Bandit head. AFAIK you can run this jug on your existing bottom end or bore out the sleeves on the stock cylinder bank (slightly more material on the B12 jug so possibly better cooling). According to the ebay seller they came off of a low-mileage drag bike and the sleeves and piston rings look to be in good shape but as always best to hone and re-ring to be safe.

I bought these off of ebay for about $250. Looking to get $200 + shipping or a little less plus a set of 1st gen stock pistons in good shape. Maybe interested in an aftermarket set for stock bore. I'll be rebuilding my engine over the winter at some point and will replace the pistons to eliminate the oil burning problem but the budget will be tight so I plan to stick as close to my existing state of tune as possible since there won't be any money available for dyno runs or other work. "

http://farm7.static.flickr.com/6076/6110066968_8c8078b650.jpg

http://farm7.static.flickr.com/6068/6110068020_5d234def63_z.jpg

http://farm7.static.flickr.com/6061/6109522539_83f895083b_z.jpg

http://farm7.static.flickr.com/6205/6110070978_48a1085548_z.jpg

http://farm7.static.flickr.com/6207/6110072028_300374ce75.jpg

http://farm7.static.flickr.com/6187/6110072974_18a4d091a8.jpg

but looks like they are now sold.

The pics...

Gus, just to warn you first, parts of my bike are faded, stonechipped and a little dirty..............


The mid pipe in silver was going to be another 4-6 weeks when I ordered, so I went for polished stainles.


Trick silver coating. Same coat on the inside to keep the temp of the exhaust gasses up.


No whopping great advertising plate, just a subtle laser etch.

Very nice - might have to save for some headers and eliminate the cat.