Author Topic: Oversize Pistons or gilardoni kit (Read 11170 times)

amamet · « **on:** July 18, 2015, 11:43:22 AM »

My 77 lemans 1 may need some cylinder work and I'm wondering which direction to go. As the 83mm drop in kit is real hard to find do I go with honing and oversized Pistons as opposed to having the cases machined to accept the 88mm kit to preserve originality
Thx
Allen
Ps the cylinders are at a shop being measured to make sure I really do need the work, the mechanic said it looked like it did

PeteS · « **Reply #1 on:** July 18, 2015, 03:24:02 PM »

25 years ago My Lemans needed a rebore. If Gilardonis were available then, I wasn't aware of them so I went with .5mm oversize pistons. At that time Guzzi pistons were sold without rings. Rings were a separate order item. I think with a rebore, pistons and rings I was out 400 bucks.
Go with the Gilardoni kit and be done with it. Nikasil is good for many 100s of thousand miles.

Pete

amamet · « **Reply #2 on:** July 18, 2015, 03:50:37 PM »

What I'm concerned with is machining the cases (which obviously can't be undone) for the 88mm kit. If the 83mm kit were available I haven't found any

smdl · « **Reply #3 on:** July 18, 2015, 04:26:07 PM »

Why not get the 88mm Gilardonis machined to fit the stock cases?

http://www.mgcycle.com/index.php?main_page=product_info&cPath=68_129&products_id=2138

amamet · « **Reply #4 on:** July 18, 2015, 04:30:21 PM »

From what I was told, the cylinders don't have enough meat to machine down

Antietam Classic Cycle · « **Reply #5 on:** July 18, 2015, 06:22:04 PM »

Quote from: smdl on July 18, 2015, 04:26:07 PM

Why not get the 88mm Gilardonis machined to fit the stock cases?

http://www.mgcycle.com/index.php?main_page=product_info&cPath=68_129&products_id=2138

Those aren't machined down to fit into the case - the case needs to be bored. Here is one source for 88s that fit without any modification:
http://www.hmb-guzzi.de/shop/Guzzi-Engine/Piston-Cylinder/Cylinder-Kit-88mm--Lm-1--LM-2.html

amamet · « **Reply #6 on:** July 18, 2015, 07:03:59 PM »

Hmb's ad does state that the cylinders are machined to fit the lemans. Are they modified gliardonis? Anyone have any experience with these?

Hahnda · « **Reply #7 on:** July 18, 2015, 07:09:38 PM »

I have used a similar big bore kit on a T3. It is what it says it is.

smdl · « **Reply #8 on:** July 18, 2015, 07:51:08 PM »

Quote from: Antietam Classic Cycle on July 18, 2015, 06:22:04 PM

Those aren't machined down to fit into the case - the case needs to be bored. Here is one source for 88s that fit without any modification:
http://www.hmb-guzzi.de/shop/Guzzi-Engine/Piston-Cylinder/Cylinder-Kit-88mm--Lm-1--LM-2.html

Understood, but the MG Cycle ad says that the cylinders can be machined, which was what I had said. Probably better to order the complete kit from HMB, though.

Shaun

amamet · « **Reply #9 on:** July 19, 2015, 11:03:09 AM »

So the HMB kit is a machined down gilardoni cylinder too. Seems that's what's available unless anyone know of a set of 83mm lemans gilardonis. I let mike rich tell me whether to open the cases or use the machines down cylinders. Again if anyone know if a set if 83's they want to get rid of, please tell me
Thx
Allen

Dick · « **Reply #10 on:** July 19, 2015, 02:13:51 PM »

I personally would prefer the over bored cases over the turned down spigots, JMO. I understand the originality thing too, so why not find a 949 block(plenty around) and use that for now. Keep your original for originality's sake? Good luck.

Chuck in Indiana · « **Reply #11 on:** July 20, 2015, 06:57:31 AM »

Quote from: Dick on July 19, 2015, 02:13:51 PM

I personally would prefer the over bored cases over the turned down spigots, JMO. I understand the originality thing too, so why not find a 949 block(plenty around) and use that for now. Keep your original for originality's sake? Good luck.

:1:

Furbo · « **Reply #12 on:** July 20, 2015, 08:30:08 AM »

Bore the cases. Plenty of space.

While everything's out, get a good machine shop to balance the crank & new pistons, etc. Not expensive, and really makes a sweet mtoor.

from memory - others may correct me, the B10 cam was offered as a race kit for the 850 LM. It was stock in the 1000cc motors. You might want to consider it as well as some 40mm pumpers to complete the motor.

PeteS · « **Reply #13 on:** July 20, 2015, 08:54:53 AM »

Quote from: Furbo on July 20, 2015, 08:30:08 AM

Bore the cases. Plenty of space.

While everything's out, get a good machine shop to balance the crank & new pistons, etc. Not expensive, and really makes a sweet mtoor.

from memory - others may correct me, the B10 cam was offered as a race kit for the 850 LM. It was stock in the 1000cc motors. You might want to consider it as well as some 40mm pumpers to complete the motor.

I think he is trying to leave the case in the bike. If he were to balance the crank then the case has to come out and he might as well bore the case for the Gilardoni kit.

Pete

Furbo · « **Reply #14 on:** July 20, 2015, 10:13:10 AM »

Quote from: PeteS on July 20, 2015, 08:54:53 AM

I think he is trying to leave the case in the bike. If he were to balance the crank then the case has to come out and he might as well bore the case for the Gilardoni kit.

Pete

Yep - that's what Im advising he do - bore the case.

Allen - additionally, you might try Agostini's in Mandello - they may be able to get you the original guzzi part, or Gilardoni's.

lrutt · « **Reply #15 on:** July 20, 2015, 10:40:04 AM »

IMO, I'd go with the upsized pistons and keep it original. I mean, how many miles do you plan on putting on this bike? Those iron bores will likely outlive you, unless you're AHRMA racing this thing.

Remember, the LM1 had different intake manifolds, will the stockers still work with those Gil kits?

smdl · « **Reply #16 on:** July 20, 2015, 10:48:15 AM »

Should be fine -- manifolds attach to the heads, not cylinders.

Shaun

Dukedesmo · « **Reply #17 on:** July 20, 2015, 10:54:24 AM »

Further to my LM2 piston/valve incident I found similar; i.e. that 83mm pistons are not easily available, as such I have ordered the 88mm Gilardonis from HMB.

HMB tell me that they are a straight fit and this is what I am expecting as I don't want to bore the cases, they should be with me in a day or so.

My cylinders are fine BTW as the damage on mine was to the pistons & valves so I'll keep the 83mm cylinders so that I can, subject to sourcing the correct pistons, put it all back to original configuration in the future should I ever want to.

lrutt · « **Reply #18 on:** July 20, 2015, 01:06:00 PM »

Quote from: smdl on July 20, 2015, 10:48:15 AM

Should be fine -- manifolds attach to the heads, not cylinders.

Shaun

brain fart on my part

mtiberio · « **Reply #19 on:** July 20, 2015, 02:28:21 PM »

you do realize there is only about a .015" or .020" difference between the 844 cases and the 949 cases? It is not like the factory made the holes in the 949 cases bigger so the cylinders would be stronger. Guzzi has this perverse desire to prevent folks from mixing and matching parts. This came to a real head in the small block series.

I haven't done it, but some one on this board opened up their 844 case with a flap wheel (a wheel of sandpaper, look it up). The cylinders and heads on guzzis float, they are not dowel pin located. this is not rocket science. I wouldn't be worried about weakening the spigots on the big bore kit by turning it down to fit the 844 case, I'd be more concerned about someone damaging the larger cylinder trying to hold it so they could turn it down in a lathe.

As long as the wrist pin and piston weigh the same (together, silly), it will probably be ok. stuffing an 88 kit onto an 83 motor where the new piston is heavier, without balancing is a sure way to make a paint shaker...

amamet · « **Reply #20 on:** July 20, 2015, 07:10:43 PM »

Engine is dismantled. Completely. Mike rich has the heads and cylinders. He suggested going big but he likes power. No issues with that. The bike needs a repaint so it will never be original anyway I guess. Most people know his reputation so whatever is done will be done well. I already had Charlie cole do the transmission. Just trying to figure what to do.

Allen

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Author Topic: Oversize Pistons or gilardoni kit (Read 11170 times)