Tuned H100SJ back from tuners, update

cb1rocket · World Chat Champion Joined: 30 Jan 2010 Karma :

Hi all, long time since any write up about my project bike, but I have since had to resort to the workshop section - yes I crashed my H100 due to a seizure and rear wheel lock up!

The power is there, apparently 20bhp of it! However it seems to over heat and cause 4 corner seizure on the piston. Anything above 60mph and the bike seize.

I'm running a 160 jet and the plug is a standard coffee tan colour so it can't be running lean, however I have a slip on expansion chamber set up and there is a gap at the exhaust port which I'm guessing is letting air in from the exhaust side and causing it to lean out due to speed of air entering it? Is this even possible?
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

What has been done to tune it? Is the timing standard?

All the best

Keith
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dougon2wheels · Nitrous Nuisance Joined: 28 Feb 2006 Karma :

Is it getting enough oil ?, had a similar problem with my mito 350, fine below 8k, but prolonged use above would make it nip up, turned out to be restrictive oil inlets on the dellorto's I was using at the time

cb1rocket · World Chat Champion Joined: 30 Jan 2010 Karma :

cb1rocket · World Chat Champion Joined: 30 Jan 2010 Karma :

cb1rocket · World Chat Champion Joined: 30 Jan 2010 Karma :

dyno graph for anyone's info, comparison versus standard.

https://i212.photobucket.com/albums/cc108/CB1Rocket/h100%20destruction/DSCI0059_zps5c2c64ce.jpg
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bypass2 · Spanner Monkey Joined: 12 Sep 2013 Karma :

what spark plug is in it BR8HS or BR7HS if on the BR7HS maybe to hot a plug

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Err, not sure if it is just the way I am seeing the pictures, but the paint on the barrel appears quite thick (almost like powder coating). Possible it is acting as insulation?

You have gone up a long way on the main jet, but not mentioned anything on the needle which could now be a limiting factor. That said, you suggest the plug colour is good.

All the best

Keith
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cb1rocket · World Chat Champion Joined: 30 Jan 2010 Karma :

bypass2 · Spanner Monkey Joined: 12 Sep 2013 Karma :

what aboat the oil pump setting may need more oil. I had a standard h100 running on a BR9HS that run allright. maybe BR9HS would help.

cb1rocket · World Chat Champion Joined: 30 Jan 2010 Karma :

running pre-mix for the time being.

No one seems to have pointed out whether a leak at the exhaust causes lean running? Does it?

Those who will remember I had a Suzuki GP100 that seize up on me several times, due to the carb cover blanking plugs missing which leaned out the mixture at speed. I'm thinking I have a similar problem but at the exhaust side of things
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

The heat range of a spark plug is down to how much insulation there is in it and how much heat it can thus transfer out of the combustion chamber.

I honestly do not know how well powder coating transmits heat (although I would also suspect that if it were powder coated then it would melt at any hot spots such as just above the exhaust), but it is something that would concern me when it appears to be a fairly thick coat on an air cooled engine.

You are at almost triple the power of the standard engine which does suggest a massive amount more heat being generated

All the best

Keith
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

bladerunner · World Chat Champion Joined: 09 Sep 2006 Karma :

From my experience a 4 point seizure is caused by over heating...cooler plug for a start...you've nearly tripled the bhp !!!!! You may want to try as cool as a 10 or 10.5 plug even rather than just one grade hotter...but this is going to be an all or nothing motor with that tune...so expect it to kill plugs if not worked hard. And as said before...a bigger main jet maybe if it's seized with wide open throttle....if its doing it at 3/4 throttle then bigger emulsion tube and probably a different needle as well. Always start big and work your way down. I know when setting up my race rgv's on the dyno....it would need maybe 4 jet sizes different in the real world and your air cooled so possibly even more difference with air temp etc......head colour looks nice and even and on the safe side if anything so I don't think your far off. What carb are you using?
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

bladerunner · World Chat Champion Joined: 09 Sep 2006 Karma :

Oh and leaking exhaust never a good thing so get that sorted however I don't think that's your main issue. Mick abbey knows how to make road bikes fast as well as race bikes...if anything I think by looking at the head and top of the piston you have a few bhp yet to gain....no sign of detonation or hot exhaust gasses causing over heating on the piston crown.....what piston to bore clearances are you using? Also it's a cast piston I'm guessing which will expand less than a forged type piston....maybe if your using a proper carb that's setup a little more bore clearence might help if your running on the close side of things?
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cb1rocket · World Chat Champion Joined: 30 Jan 2010 Karma :

Vincent · Banned Joined: 16 Oct 2006 Karma :

What pre-mix are you running? Does look a bit like lack of oil. Do you use a lower ratio for running in?
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m3-paul · Spanner Monkey Joined: 03 Feb 2009 Karma :

To me that looks a little lean from the plug colour or maybe the flash of the camera has washed the colour out too much?

I went up two sizes on my TZR250 just with new pipes. I would go up a couple more sizes on the main on the basis you also have a pod filter and look at the oil pump. That exhaust collar looks too clean.

Mine have a light oily finish but then my oil pump is more towards the rich side to avoid seizure, but, I have never had a problem with oiling plugs.
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Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

It's seized where the thickest part of the aluminium is on the piston. Overheated I would say. You might be able to rescue the barrel since that nikasil coating is goddamn hard, but the piston is clearly trashed.

Kickstart's point on the barrel coating is valid - what is that?
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132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Vincent · Banned Joined: 16 Oct 2006 Karma :

I don't think the barrel is powdercoated, you can see a few bits where it's come off in the top pic. I presume it's a gloss VHT paint, still could insulate the heat mind.

I know of cases where barrels have been powdercoated with no bad effects........ but only on single four strokes.
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Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

I am not certain on the coating, it is just something that concerns me especially on a bike putting out around 3 times the power of standard (and so generating far more heat).

Think in theory being black should slightly increase the heat transfer, but the type of coating could more than counteract that

All the best

Keith
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P. · Red Rocket Joined: 14 Feb 2008 Karma :

Know nothing about these but I'd back up Kickstart in carb size. I have a VM22 which is a 26mm carb on my 14hp bike running a 90 main jet standard but for road use it requires a 110/115 if you want to do any form of speed.

The minimum you can have is a 26mm on that and its a 140cc with less power.

misscrabstick · Crazy Courier Joined: 05 Jul 2013 Karma :

Same as Kickstart when I looked at the barrel I thought that paint looks thick anyway, that piston in my opinion has suffered due to excessive expansion/overheat, see this page

https://www.theultralightplace.com/pistons.htm

Some useful diagnosis tips there on piston failure.