Bike needs new rings

[JimBoUK]

Hi,

I'm rebuilding a GPZ1100B1.
It has standard size bores. The bores and pistons are not warn beyond tolerances in the workshop manual but it does need new rings.
2 of the bores do have very a "very slight" score from top to bottom

Question is what do I do now.

A set of standard rings from Z-Power with owners club discount is £226.47
I can get a Wiseco set from the US for under £500 with postage but I'm not sure how much import duty I'll have to pay
Eastwood racing do a Wiseco kit for £665.20

Should I just go with the rings or is the Wiseco set worth the extra cost ?

What benefits apart from everything new and perfect will the Wiseco kit give me ?

There are 2 Wiseco options. A K1136 kit for 1135cc and a K1171 kit for 1166cc. Any advantage/disadvantage with each one ?. I guess the 1135cc kit could be over-bored in the future to 1166cc.

Am I better getting a Wiseco kit from UK or US ?

What will the re-bore cost me these days ?

Thanks

[zed1015]

For the cost difference between just a set of stock rings or a complete Wiseco piston kit with all gaskets etc the Wiseco kit wins every time and the bike is going to run a hell of a lot better for longer than a sticking plaster fix of a hone and new rings.
I now buy nearly all my parts from the states and they work out cheaper than buying here in the UK even with the import duty.
Cutting out the middle man accounts for a big saving.
If you order from Murdoch racing or garyhl2004 on Ebay etc they usually send labled as classic motorcycle parts at a lower declared value etc and you only get stung for vat.
https://www.ebay.co.uk/itm/WISECO-K1136 ... xyOM5RZX0j

The last Wiseco set I bought from MRE/Gary landed at a touch over £440 to my door and avoided vat and duty.

[Swirl]

Or you could try IMD pistons and ask about there forum discount

[Al]

All of the above, and if you can still get the right ones, the 1135 kit gives you the option to overbore at a later date unlike 1170 where the barrels are written off when they need boring. There will be no noticeable difference in performance batween the two assuming both have the same compression ratio which is not a given.
The guy who did my last rebores charges by the 'pass' so going from 72.5mm to 75mm is more than one pass and therefore more than one rebore!!!
There is a very remote possibility that i may have some good used oversize pistons, no promises as they may be Unitrak but that would allow you new rings as you had planned and a rebore to clean up the scores. Would you like me to have a look?

AL

[zippy]

I've got a Wiseco 1170 kit if you're interested.New boxed with gaskets, bought for my B2 but ended up putting unitrack head on so needed different pistons.PM me if interested.

[RAYZ1]

I rebuilt my freinds gt750 engine which I got in bits , one bore was badly marked , honed it , with the rebuilt crank it runs a treat and the flight score makes little difference - perky as hell , better checking all your valves carbs and ignition , to chase a couple of HP , the risk of the boring shop making it worse plus the expense over and above the raw cost of pistons / depends on how bad the score is ultimately/ did you do a compression test before you stripped it ?

I saw s picture of 500h1 ports where factory casting residue would partially cover the ports , nobody could probably tell in all it’s years

[Mr Bump]

There's a coincidence - I'm just going through exactly the same thought process. Ive got an 1100b2 with the head and barrels off it, initially for repairs to some duff cam bolt helicoils.

While I was there I got carried away and decided to get the head and barrels powder coated, the powder coater offered to get a couple of damaged fins welded, the welder dropped something heavy on the barrels and broke a chunk off of one of the sleeves. Arse. All is settled up with the powder coater (who did an excellent job of the actual coating) so no grudges borne, but...

I've got a set of lovely finished barrels on decent standard bores, but one shafted liner, a set of 4 decent enough pistons that appear to be within tolerance, and a set of shafted rings, and I'm considering whether to just get another liner made and buy some rings, or go mad and fit the smaller wiseco kit.

Half thinking of buying a set of shabby barrels for one of the liners, pressing the liner into my nice smart barrels then having the lot bored out. Are there any drawbacks to the 74mm wiseco kit? The compression goes up a bit, does it get peakier or stay nice and torquey? Any risks of running hot? Much rejetting required? It's on bs34's.

Any advice appreciated.

Thanks,

Olly

[Al]

Olly, there are four 1100cc liners here for £10 each.
https://www.ebay.co.uk/itm/KAWASAKI-Z1- ... Sw6-5eLbou
These are 1089 barrels / liners and although the fins are bust off, the liners could still be OK. Cant comment on bore size as the seller knows nothing about what he's selling. They could already be 0.5mm oversize.

Nothing wrong with the 74mm kit and makes more sense as you can bore up later if the worst should happen. Yes comp. pressure does go up but you can mitigate that with cyliner spacers or valve timing. I believe the MLS head gaskets may come in different thicknesses but dont quote me on that. I used to use two thick base gaskets to lower mine a little.
You will see increases in both torque and power with that bore size plus the Wiseco pistons are far batter in many ways than OEM ones and rings, pins and clips are and will be readily available for years to come. There is no significant risk of running hotter but it is still an air cooled engine and needs to be used that way. Again there are many ways to keep it running cooler if it gets that way but of itself the relatively small increase in CC will not cause issues of that type and forged pistons will resist the fractionally harsher environment far better than OEM of the same size would. You may need to re-jet it either up or down depending on youre existing setup and how hard it pulls on vacuum. Youre other post about BS34 mm carbs might be key here. I agree with Mark that airbox is best, as for jetting and slide cutaway etc etc i cant comment as i have no knowledge of 750 settings.

http://www.wiseco.com/ProductDetail.asp ... AppID=7901

AL

[Mr Bump]

Olly, there are four 1100cc liners here for £10 each.
https://www.ebay.co.uk/itm/KAWASAKI-Z1- ... Sw6-5eLbou
These are 1089 barrels / liners and although the fins are bust off, the liners could still be OK. Cant comment on bore size as the seller knows nothing about what he's selling. They could already be 0.5mm oversize.

Nothing wrong with the 74mm kit and makes more sense as you can bore up later if the worst should happen. Yes comp. pressure does go up but you can mitigate that with cyliner spacers or valve timing. I believe the MLS head gaskets may come in different thicknesses but dont quote me on that. I used to use two thick base gaskets to lower mine a little.
You will see increases in both torque and power with that bore size plus the Wiseco pistons are far batter in many ways than OEM ones and rings, pins and clips are and will be readily available for years to come. There is no significant risk of running hotter but it is still an air cooled engine and needs to be used that way. Again there are many ways to keep it running cooler if it gets that way but of itself the relatively small increase in CC will not cause issues of that type and forged pistons will resist the fractionally harsher environment far better than OEM of the same size would. You may need to re-jet it either up or down depending on youre existing setup and how hard it pulls on vacuum. Youre other post about BS34 mm carbs might be key here. I agree with Mark that airbox is best, as for jetting and slide cutaway etc etc i cant comment as i have no knowledge of 750 settings.

http://www.wiseco.com/ProductDetail.asp ... AppID=7901

AL

Thanks Al, all very helpful.

Why did you want to drop the compression back a little? There are all sorts of effects raised compression could have, I'm interested to fully understand how the character of the motor will change if I fit a 74mm kit, and if I'd want to reduce the compression a little too.

Olly

[Al]

Long story. Go back twelve approx years and Wiseco piston kits came supplied as very raw cut pistons with very shape edges to the valve pockets, useable fibre one piece head gaskets, and paper thin base gaskets. They also came in different compression ratio variations for some types. Now; they have 'Race Ready Domes' (they have polished all the edges smooth), MLS head gaskets, and apparently no base gaskets, (least not in my more recent set) though it could just be missing.
I had a knackered Dyna 'S' a bent advance and retard unit(incorrectly shaped drive peg) and CV carbs and wanted to go racing! Then begins; pinking, oil leaks from the head gasket, miss-firing, and all the other issues associated with a bad set-up. After many knee-jerk actions including putting two base gaskets in, i gradually removed the issues with Dyna 2000, polishing the crowns, MLS head gaskets and a decent single thick base gasket. Overtorquing the head gasket was causing the base gaskets to squish out,... see what happened there. Along the way, i had taken to revving it to 11,500 RPM which was OK 'till the pistons hit the head. During this sequence Cometic appeared to use softer and softer compounds for their fibre head gaskets, which no matter how hard you torqued them would not stop leaking. Another reason not to use two base gaskets. As a matter of interest i still have the same Dyna 2000,, now with RS flatslide carbs and those same pistons which look absolutely mint after; numerous drag race passes, numerous sprint events, many road miles here and abroad and eighty plus track events. They are however on their second set of liners and about sixth / seventh set of rings and circlips. When i originally bough t these there was a serious supply problem in the UK. Think i waited about nine months or so. When i got them i installed them and never gave it a thought. Four years ago now i had them in my hand and was in front of a very accurate low range weigh scale. So one turned out to be massively heavier than the others, three were exactly the same and they all looked identical. So i guess that someone nicked one out of the kit and replaced it by purchasing a single item. I lightened the heavy one and as said above, these are still that same set i originally bought!
To answer youre question; the higher comp, pressure is noticebale when you ride it and it feels slightly reluctant untill it over-comes its pumping phase but higher compression is a way to gain efficiency and yes its not without its issues. Cranking pressure can also go up slightly.
AL

[zed1015]

AL.
Just bought a couple of new Wiseco kits with MLS head gaskets and they both came with a base gasket too so I think you have been unlucky.

[Mr Bump]

I'm 98% sold on the wiseco path I think. Thanks for your advice al, very helpful.

Olly

[Swirl]

I'm 98% sold on the wiseco path I think. Thanks for your advice al, very helpful.

Olly

Imd also do piston kits to BobbuZ1085 has had a set in his for many years it gets rode hard with no issues

[Al]

AL.
Just bought a couple of new Wiseco kits with MLS head gaskets and they both came with a base gasket too so I think you have been unlucky.

Someone got my base gasket but i had their head gasket, it has two.

Just had a look at IMD site and searched for; GPz 1100 and for ZX11 and Unitrak and 1135 and 1170 and zero results for any of these!

https://imdpistons.com/collections/perf ... iston-kits

AL

[ADRIAN H]

Just had a look at IMD site and searched for; GPz 1100 and for ZX11 and Unitrak and 1135 and 1170 and zero results for any of these!

https://imdpistons.com/collections/perf ... iston-kits

AL

You may have to phone them up.