Engine rebuild

[benny hedges]

maybe fit a set of these tony

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... _500wt_691

mine does the same at 7k with full throttle. i dont think the standard springs can take the extra power.
must be a good boost eh - swap bikes again at bulldog

[tony.mon]

Barnett uprated springs already fitted, but I'll check free lengths, maybe add a spacer with each, if they don't get coilbound at full compression.

[bandsawman]

Fi?
I might as well just give in and buy an SP1 or 2, which was an option, but I'd rather play against the prevailing wind this time out.

Probably more sensible, but

Let's see what's possible with what I've got......

That's what I like to hear!

[benny hedges]

Fi?
I might as well just give in and buy an SP1 or 2, which was an option, but I'd rather play against the prevailing wind this time out.

Probably more sensible, but

Let's see what's possible with what I've got......

That's what I like to hear!

was talking to a guy this morning who amongst other stuff has a gen sp1 wsbk engine.... could not persuade him to part with it lol but i will persist!
apparently the rods are a 1000 hr item mega maintenance motor!

[tony.mon]

Booked a baseline dyno run for Wednesday next week, so I'd better get the clutch sorted this weekend.

Wonder what it'll show me?

[benny hedges]

nice one tony - look forward to the results...
make sure the chain is adjusted & lubed nice too... and run on super unleaded!

[sirch345]

Good one Tony, I look forward to hearing the results too

Chris.

[tony.mon]

Just got the bike on the dyno, and the headline figure with 10.5:1 pistons, and standard cams and airbox, is 113 Bhp, max torque 73.
Not too bad, because there's cams and the ignition advancer to go in yet.
That run is in blue.

Then I fitted that airbox I had gutted, to see if that would make any difference. It doesn't really, loses .7 of a Bhp and messes up the fuelling at about 3500-4000 RPM.
That run is in red.

I'm thinking that the airbox volume is bigger; therefore I should have seen more of a difference than this, but it may well be the inlet snorkel, which I've always thought seemed a bit small (cross-sectional area) for the size of the carbs.
So before I give up on the airbox mods I will try modifying the snorkel to make it less restrictive, and dyno it again.

But the fuelling is off; it runs lean now as you can see from the stoichiometric traces below the main panel.
Normally I would have this sorted, but as I'm trying to do direct comparison runs so that I can see what effect each change has, up or down, and how many Bhp, I'm going to leave that 'til last, then have it readjusted to get as good fuelling with all of the trick bits in as is possible.

Lastly I had it run through the gears; and this was the result:


So there you go; lots of money and time for some gains, but not huge. But let's see what the cams do; I'll be perfectly happy with 120 reliable Bhp, to be honest.....best I've had before with a Factory Pro jet kit, standard cams and pistons, was 106, so I can say that fitting the pistons gained me 7 Bhp. (but this is without readjusting the fuelling, which would probably liberate another 1 or 2).

However the previous runs I've had didn't show torque figures, and it feels a fair bit torquier low down.
Certainly it lifts the front end pretty easily on the power in the lower gears now, which was a noticeable difference.

Anyone got a dyno readout with a standard engine showing the torque trace to compare it to?

[benny hedges]

nice result imo tony m8... thats a very smooth power curve and tbh that fuelling is about as good as you will get for carbs...., you saw what mine was like lol, went right below the line.

i reckon some slight tweaks here & there and it will be bob on.
better with a smooth output like that than a peaky motor imo - well done bud...
look forward to seeing the result with the cams

might be worth asking the operator for a stored run of a standard one?

[sirch345]

Cheers for that report Tony, very interesting to read what difference is had by just fitting the higher compression pistons Personally I'd be happy with those results It'll be interesting to see what difference the modified cams make when you have the time to do that. Even if you didn't fit the modified cams you must be pleased with how the bike performs as it is now.

Does the higher compression pistons make the engine vibrate more have you noticed

Chris.

[Darknomad]

how mutch did it cost for a dyno run?

im toying withgetting a jet kit and filter after ive done my forks
after those two maybe a new rear spring suspension solution
it goes on and on i love it

[tony.mon]

Chris:
Not really more vibration, but you can feel that the bangs are stronger.
Not sure if I've described that very well.....

I paid £50 for about ten runs, including leaving it on the dyno while I swapped the airbox over.
But they know i'll be back a few more times before I'm done.

But as a guide I paid £150 for a Factory Pro jet kit to be fitted, and set up.

I'd definitely recommend HM Racing, they've just moved to lovely big new premises in Edenbridge, Kent.
And I helped pay for it!

[sirch345]

Chris:
Not really more vibration, but you can feel that the bangs are stronger.
Not sure if I've described that very well.....

Cheers Tony, that's described well enough for me

Chris.

[tony.mon]

Today I fitted the reground cams I had done last autumn.
They are about 1mm higher, with about 10 degrees more dwell.
I set them as per the standard ones, didn't degree them in, so may not be as good as they could be yet.

But rode it around for ten miles or so, TBH knackered so didn't want to be out for long.
Preliminary seat-of-the-pants impressions is that it's gained a few BHP, maybe five or so.
But it's more "cammy" so feels stronger at the top end but maybe less torquey lower down.

It might be just that in comparison to the increased top end the torque hasn't increased; we'll see what the dyno says.

I will dyno the bike "as is" to get a true comparison standard vs. reground cams, but then I will refit the long intake trumpet on the front cylinder instead of the standard short one currently fitted. I wanted to leave everything as standard as possible for realistic dyno numbers, but will add the longer one and a -4 degree ignition advancer once I've finished the comparisons.
That should get me some of the torque back again.

But a big improvement over standard, both in terms of power and driveability.

Dyno figures to follow, probably next week.

[benny hedges]

mine feels a bit like that with the new came toe, like its got a power band over 6 - 7k, between there & the limiter it goes nuts!
to take advantage of that i run 2 short stacks instead of the one short one long.
will be interesting what the dyno shows, but i agree with the dialling them in.... the dyno chap i go to does all roger's engine runs for him & said theres a lot to be had yet with some slotted gears.... might have to invest one day.
but to do it proper i'd just leave it with them & save fkin about.

sort of goes against my ethos of doing it all myself like, but there's practicalities...