Add me to the list......

POP.......My nsr at oultonpark today

sizzle.....My £2 bbq

YUM.......me eating the the mint lamb kebabs made on my £2 bbq

Oh well time to take the bike apart and see whats what..

It happened like this.

First session i did she was running fine.. going well no problems.

second session she was difficult to start, with FONTYYY AID i got a push and it fired, all seemed well!!!

In the holding area, temp started to rise quickly????? (dosent normally do this, and it wasnt a hot day)

Went above 80 i was about to kill it but we where let out on track. first lap she was unresponsive and still hot!

second lap she had cooled down to 60 odd and started to come back on form.

3 corners later she stop firing, felt like jamming your brake on hard!!! but didnt lock up.

I clutched in and stoped the bike, selected netraul and that was that.

Back in pits she turns over but is VEry very easy to push the kick start.

No idea what ive done but ill find out soon enough, sugestions here from you chaps might help when im looking for things,

Got some hints tips from FONTYYY but intrested to know if anyone else has had a similar experiance?

Oh yeah and the lamb kebab things where nice

Long way for a £2 bbq LOL

Welcome to the club Just whip the barrels off and good luck.A lesson I've learnt is that if the bike starts to do anything unusual like the temperture starts to rise, it starts missing or it has trouble starting is stop and have a look as its normally the start of a big problem,For example:-at llandow last year mine started missing towards the end of a session but would clear under hard load,when I tried to start it for the next session it would'nt tick over but would rev OK,2 laps in to the next session it stopped,it broke a ring, destroyed a barrel,piston and head,if only i had took a look at the motor earier I might have got away with just a new ring.

Yeah, i should have knowen better LOL oh well that top end rebuild has just come early!!! question is, do i repair or buy that 300 kit!!! init self will have issues i guess!

In the classifieds Stephenrc45 is selling a 300 kitted 21 motor,It was build by Stephen himself and he knows what his doing, Myself, Fontyyy and Andy have rode Stephens 21 when the motor was in it, its a good'ern,if you compare it to the cost of the 300 kit then its a bargin as you get the whole motor,buy it ,you could have yours back on the road at the weekend with 70hp on tap

if you can kick it over easy then at least you didn't dig a piston into the cylinder. That's something to be happy about
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Charles Gallant

Yeah she kicks (well i did it by hand) over freely with a bit of compression, Monkey and billy think its the front oh well,

Ive already mailed stephen, and will let him know this weekend! i was gona 300 my bike and this would be a good thing as then id have mine as a spare engine! but i need to sort a few things out and get back to him. it may come down to cash!!!!!!! maybe he'll take install ments LOL

Ho hum!!!

A compression test or pulling off the pipes and peeking in the exhaust ports should tell you all you need to know.300 is prime though set up can be tricky if you set to kill, but its worth it!!
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1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike

yeah im gona do a compression test and see what i get at least ill learn LOL, not sure i wana peek inside might see horrid things. maybe ill do it blind folded then it wont look so bad!

Do fancy the 300, its gona cost me a few quid to put this right, thats what im gona work out first, depending on the damage!

Right.......... Got home a bit early today and had a look see, I haven’t taken the heads or barrels off but I found out which ones has gone. I’ve been told 9 time out of 10 it’s the front/bottom piston that goes POP, I took the spark plug out ....mmmm....golden brown.. Lovely, managed to get the compression tester on and it 118psi gooooood,

Now to the top back one, took out the plug and errrrrrrr its grey, uh Oh! Found it, I couldn’t get the compression tester on it, but looks fairly obvious that it’s the back/top piston/barrel that’s gona need looking at will keep you posted on what went wrong!

Is there a chance the plating will be ok or is it fairly certain that ill need to have it done?

Found this today im sure most of you know what to look for but apex have an interesting page on there site!! Turn away if you’re mechanically squeamish

http://www.apexleisure.co.uk/pistondiagnosis.htm

I just broke a dime size piece of my piston off and it was smeared into the cylinder wall. Some muratic acid and a ball hone and its as good as new.
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1995 A kit TZ 250
1994 Rothmans NSR 300sp SOLD
1998 RM 250 freestyle/motorcross
1998 Meathanol burning CR 500 AF super retard/motorcross/sand dunes/play bike

If the top one has gone normally something else is amiss, check you've got the right heads on the right barrels, i.e. not an R barrel and an SP head on the top. Also while it's apart, have a look what jets it's running, in theory it should be a size (or maybe two with the head conversion) leaner on the top.

Put your finger over the plug hole and push the kickstart, you should feel pressure, a fiver (and the feel of the kickstart when I was there) says there'll be nothing there.

Have fun, chopping the top is a pain, tank off at the roadside unless you live at the top of a rise just after a 120mph straight

Re. will the barrel live without a replate? Maybe, it'll certainly have some level of damage and no pro engine builder is going to recommend running a damaged barrel at all, but there are several out there running fine that I know of with pitting and/or a cracked bridge.
You wouldn't think mine would last if you looked at it, there's some pitting on the bridge that you can feel. I was dubious but Steve said it'd be OK and it has been.
It depends how you view it and what you want, if you want it as reliable as possible and don't give two hoots how much you know about what's what then have a reputable builder fit a new Honda barrel (or replate yours) and piston kit, follow their running in guide and get it back to them to check the jetting. But as you've found having someone else do it is no guarantee it won't go pop when used in anger, there is no substitute for real world testing. It's also going to cost somewhere the wrong side of £300.
Or rip it down and see how it looks, you never know, you might get away with a bit of wet and dry on the barrel and a new piston and rings.
And that's my point, knowledge of what will or won't work comes from finding out, sometimes the hard way.

Or talk to Andy, he loves taking them to bits, he wanted to swap my barrel the other weekend for no good reason

This in no way condones the use of less than perfect parts, do so at your own risk
or when you realise the piece of outdated junk will die anyway, no point burning a £50 note when you can burn a fiver and get the same result!
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

Yup, we will have to see, the offers comming forward to assist is amazing, iv had some info from matt regarding rebuild options, what to look for, matching pistons etc. iv been emailing steve back n forth about his motor and the possiablity of getting mine rebuilt by him and Andy. and cheers Fontyyy for the advise and links.

Shell be back up and running soon. then ill ring its neck for being bad!!!


How do i tell if the head on the rear is right for a B barrel or R model? I know when i did the front conversion i ordered a "R" head from Matt so i know thats okay! but no idea how you tell!

The barrel diameter difference is tiny (as in thousandths of a inch), all the R or SP heads are the same (i.e. there are essentially only 4 '21 / '28 heads, front and rear both in R and SP form).

The head will have either KV3L or KV3H embossed on top (it's part of the casting, it's not just stamped).
The barrel will have either L1, L2, L3, H1, H2, or H3 on it at the bottom on the other side to the powervalve mech.

The H means it's from an R model
The L means it's from an SP

The SP head has a smaller squish area for higher compression, this is not suited to normal road use and 95ron fuel with an R barrel.
The SP barrel is taller to put the squish back to normal again on the Se and SP models.
It was just a trick to give Honda higher compression for the racebikes with std parts.

Check both the head and barrel are the same, that's what matters, not if it's SP, R, 21, 28, A, B or whatever, they all fit and work.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

right if what your saying is true the bike has L1 barrels both of them, the rear head (the one thats poped) is a KV3L and the front which i replaced and assumed is a R is a KV3H Doh,

So should i seek a Matching KV3L head for the front as well or is R head on a SP barrle ok??

Wonder why an R modle has L set up?

Right then,

from the top;

L is SP stuff;
SP head has small squish (higher compression)
SP barrel is tall (lower compression)

H is R stuff
R head has large squish (lower compression)
R barrel is short (higher compression)

So the SP head, R barrel is the combo for a race bike c/w some kind of wacky fuel to keep it from detonating itself out if existance.

Either R,R or SP,SP is std for a roadbike, I believe they are both exactly the same once togeather.

R head SP barrel would make a low compression setup.

So the front is running too low a compression (in comparison to the rear) and I'd therefore guess the front is not working hard enough, the rear is overworked and has died. You need an SP head on the front, your old std front SP head would be better than the R you've got now.

Matt? Andy? Steve? Any thoughts?

How does the barrel look?

As to why, it's 15 years old, it's had a rebuild or two for sure, if you buy a barrel/piston and head 2nd hand it's of no concern wheather it's R or SP.
I wouldn't even bother asking, just make sure it's right when you bolt it togeather.
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Please do not PM me technical questions, if you can't find it on the Forum start a thread