It's a long way to 920 type(rary)

Dances with Shrapnel said:

There are three main aspects to squish; quench, getting more air/fuel into play for useful combustion and creating turbulence.

• With quench there is a diminishing return on suppressing detonation. I cannot cite the classic references but anything less than something on the order of 0.030 to 0.035 will not gain you anymore with regard to suppressing detonation so more (tighter squish) is not necessarily better as you will not gain anything here.

• Getting more of the Air/Fuel mixture into play with a more central combustion chamber mass around spark plug is always a good thing provided there are no significant detriments to port/valve flow. If you know your squish area, you can calculate the volume based on clearance and compare it to the overall combustion chamber volume - maybe expressed as a percentage.

• As for turbulence, one needs to weigh out how much squish area you have to work with. There is an ideal ratio of cylinder area to squish area. In this case, more might be better but again I read somewhere about excessive pumping losses due to too much squish area and too tight a squish clearance.

So, once you get adequate quench to suppress detonation, closing down the gap any further gets a bit muddy,.........so it depends.

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HI Dance, I will keep this in mind, I will not go under .035" or .040 to be safe
Thanks
Yves

I was told by CR Axtell many years ago to set the squish on a 750 Commando for racing at .040" to be safe. That was for conventional stroke 750 engines with stock rods and crankshafts. I've used that for my guide ever since. I have run as little as .035" in some cases with no problems. The only Commando engine I've worked on that had the squish set at .020" was an 872 race engine with stock cases, billet crank, and titanium rods, and the pistons hit the head hard enough to break the crankcases at Laguna Seca. I'm pretty sure this engine was revved well above 7,000 rpm regularly on the track. I rebuilt it as a favor to the owner, who insisted that I set the squish clearance at .020", as the previous builder had. I set it at .040" anyway, and the bike survived the next race at Daytona with no problems. Other people have different experiences and opinions. I'm just offering my experience for whatever it's worth.

Ken

Hi there, I receive the .021" / .51mm from Jim Schmidt last friday, but I will whait one or two weeks to do the job becouse I have problems with my healt: I will be 68 at september and I have already 3 hart attacks behind me, but no problems anymore in the last year, till last friday, I made a apointment with Bruno to finish some work on his bike, when I wish to start the work I feel dizzy, very dizzy, and the need to vomish, I sit on a chair and the light go out, my light, not those in the workshop.
Bruno weak me up and want to bring me to the emergency from the hospital from my city, I say no, bring me home please. once at home the things go worster, my wife call the dokter and he find that my hart was overeving, then stop, then start again and so on, he give me some medecin and I go to bed, after a good sleep wake up in better shape and go to the workshop to finish Bruno's bike and then go home and rest. To day I take my Seeley to go to a rally, 200kms, no problems with the bike and a bit problems with me, feeleing very tired.
I tell you this story to explain you that I will spend next week for my own healt, I will go to the cardio and so on to see if the head gasket of my hart is not blowing away
and I hope to be at Spa next WE
Thanks Bruno for the way you take care of me
Keep you posted
Yves

Quite right, put your feet up and chill out for a week yer daft bugger !!

The new cylinder head gasket will still be there afterwards...

Take care Yves, your lovely Norton will still be there willing an waiting once you are in better shape to carry on.
Great description of your problems related to your bike !!!

I will go to the cardio and so on to see if the head gasket of my hart is not blowing away

Regards Mike

Take care of yourself Yves.

Yes, Yves was really feeling bad on Friday when we wanted to finish my Norton for the WE, he never let me take him to the hospital so I took him home in his car where his doctor promptly came to see him. He was feeling better yesterday morning when I went back to get my Norton back, but still not 100% and yet decided to take his Seeley for a 200km ride with Pierre, another friend. Most of you have never met Yves in the flesh, I can tell you that his pigheadedness is as larger than life as he is...
I cross fingers that he accepts to rest a bit this week to get better!
Thank you all for your encouragements, Yves is very thankful to the group for all the support!

Yves, the most special thing about your bike is YOU, and the passion you have to build such a beautiful machine. Take a few days off and let the doctors sort you out, much like you would do if your bike had a mechanical problem. Rest, get healthy, come back stronger...

Hi there,
I wish to thanks all of you for the support, also by PM and emails, to day I start the medical examinations, but I feel already better with your support
Thanks
Yves

Hi There,
I spend the whole week with doctors, I deed a blood analise, everithing OK, no diabetes, no cholesteroll, good to know that I am still a Rock and Roller and not a Cholesteroller. A visit to the Cardio was also positief, next week I must wear a electro cardiogram for 24 hours.
The conclusion from the Doctors so far: It must be something in my ear that make me dizzy and make me see siek, but believe me, it was like receiving a upercut.
The danger is when I ride my bike, imagine that I met Mike Tyson underway and he knock me down...
To day I was at Spa-Francopchamps, 300 kms on the Seeley, no problems with the bike...
The organisator from Spa classics are very smart, but like the most of the smart persons they think that the others are stupid, a few years a go you see Agostini, Read, Redman, Sarron, Bakker and more top riders, now nothing more, but the entry prize is more expensive as before, only in the Side Cars a few ex- world champions like Steinhausen, Werner Swartsel and Bornhorst.
I was expecting to met Steve A or Storm, I don't find him; I find Martin Page from Minnovation, a nice man, and he tell me that I will maybe take the business from Maney over, thats good news!!
Next week I will go back to work on the 920, I will put the .021" / 0.51mm cooper head gasket from J. Schmidt to replace the .025" / 0.66 mm
If my calculation are good I will have a squish from .040" / 1.1mm
Keep you posted

Nice to hear all seems well Yves.

So, your idea of putting your feet up is to take the head off again is it ?!

Fast Eddie said:

Nice to hear all seems well Yves.

So, your idea of putting your feet up is to take the head off again is it ?!

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Éternel recommencement...

Fast Eddie said:

Nice to hear all seems well Yves.

So, your idea of putting your feet up is to take the head off again is it ?!

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And maybe strip the whole engine becouse I have a small oil leak at the crancases

yves norton seeley said:

.......
I was expecting to met Steve A or Storm, I don't find him; I find Martin Page from Minnovation, a nice man, and he tell me that I will maybe take the business from Maney over, thats good news!!

Keep you posted

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No Yves, Spa is as you say, far too expensive, I have entered Gedinne in August!

In two weeks we will go south in France for my last French VMA ride of the year.

Minnovation have been building bikes using Maney stuff for some time and come from the same mining equipment background so there is both logic and continuity in that plan.

Hi there
This monday I take the engine out the frame to put the .021" / 0.51 mm cooper head gasket, my first idee was to strip the whole engine for control, but I don't didn it.
Anyway it's easier to put the head off and on with the engine out of the frame.
Yesteday I tchek the squish clearence: .040" or 1mm, must be good no?
After I put the head on with Pliobond and put the engine back in the frame; I strip also my TTI gearbox to remove the kick start mecanisme, no need anymore with the Alton estart, I make a piece of alloy to feel up the hole in the cover, flush with the casting, beautifull...
I also change the place from the J.S. PCV valve from the back from the crankcases to the side of the timing cover and replace the plastic hose with Aerokip SS hose like all the other hoses on my engine, details, always details you know...
Tomorow I will put all the stuff around the engine and I have to make the carbs ritcher over the whole RPM range, when I take the head off, the pistons top was to grey, no detonation but to lean
I hope to have the bike runing tomorow eve
Keep you posted
Yves

Hi there,
Yesterday I start the engine for the first time with the .021" / 0.51mm cooper gasket and the .040 squish and to day I did a ride from 100 kms.
Like I say in my previous post, the carb setting was to lean, so I put 3 points higher on the main jet, turn the fuel screw open to 1.5 turn and rise the needle 1 notch
and here is what happens to day, as long you don't do a dragster start, no problems, but when you go to 6.200 RPM in first gear and go WOT in second, the engine is like not receiving fuel and this happens only in second gear, tomorow I will rise the needle one notch more and tchek the accelartion pump and will search the perfect settings on my Keihin 35 FCR.
I gat the feeling that the squish as a big influance on the carburation??
Keep you posted
Yves

yves norton seeley said:

I gat the feeling that the squish as a big influance on the carburation??
Keep you posted
Yves

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Has your compression ratio changed? I understand that changes in compression ratio usually require changes in jetting.

Hi there,
To day I feel very happy, it's take me 10 days to find the problems with the Keihin FCR 35, but I have first to face another problem: you know that I use a Alton Estar, when you buy the system you receive a inner chain case, and you must put this case on the crankcase with 3 bolts, just like original, but there is no way to put a original safety washer, so here is what happens: one off the bolts was comming lose and destroy the Alton rotor, so I have to order a new one and repair the whole thing, including a new needel bearing and inner race, this take me a few days away from my carbs problems.
When the starter was fixed, I start again with the carbs, changing main jets from 145 to 152, trying different needels and so on, but nothing was going better till to day:
You know that I change my K&N for bell mouths, so what I did I put the K&N adapters back on the carbs with the K&N fiters and I rise up the main jet from 152 to 170 becouse I don't have something between, I did a test ride and the bike was flyhing as never before, Of course I have to search the reason for this miraculous fix, it can be the change from the bell mouths to the K&N or it can be rising the main jet to 170, the spark plugs are brand new, so difficult to see the colour; but I wish to enjoy the resurection of the Seeley and I plan to go to Chimay this WE
Keep you posted
Yves

yves norton seeley said:

Of course I have to search the reason for this miraculous fix, it can be the change from the bell mouths to the K&N or it can be rising the main jet to 170

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Either way your carb setting seemed way too lean!

Yves, my dyno testing showed that the velocity stacks make only a VERY small difference. Meaning less than 2bhp, which is basically something you wouldn’t feel.

So my money is on the difference being the main jets...