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My MC18 track toy.


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NickoPen

 
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My MC18 track toy.

Sat Oct 07, 2006 7:00 am » Post: #1 » Download Post

I've posted this on another forum, but thought I'd share the fruits of my labour with you guys seeing as you've all been such a great help...

A bit of background - I saw an ad for a track toy on a forum. The owner had it for a few months but never got around to getting it running, and the previous owner had it sitting in mothballs for a couple of years, but it seemed to have compression when I had a look at it and all the bits were there plus a few spares so we took the gamble and got it.

We generally got in and inspected, cleaned and flushed everything except the gearbox oil. The radiator has about a million little holes in it, and there was a fair amount of crud in the cooling system, brakes didn't work at all etc, but we got it running, I did a track day on it, met a guy from the forum here and spent most of the day fixing the dodgy clutch cable routing.

It didn't sieze on me at the track, but it didn't run too well either. Still had stock jetting, despite running premix. It sat around for another couple of months following this with me doing the odd bit here and there until just recently...


<SNIP>
So, I stripped the bike as far as I dared and had a look at the top end. The pistons look near-new, with only slight carbon deposits, no blow by, good piston to cylinder clearance etc. There's still hash-marking on the cylinder bore so its probably only a couple of hundred k's since the last rebuild.

Then I went to the (Aussie) GP and bought a HRC jet kit from B-Components. Came back, installed it, took the bike for a ride and even though it ran a heap better than before, it was still a bit lacking. So after I decided to go and get it properly dyno tuned by someone who know's what they're doing.

Here's the dyno chart: http://members.iinet.net.au/~nickopen/NSRdyno.jpg

The green line is as I gave the bike to them. The red line is after they unplugged the factory restrictor and the black one is after the final tune.

The fuel-air ratio is a bit bumpy up the rev range due to the bike vibrating and the needles moving about a bit apparently. Its a bit rich because I didn't quite have the right jet sizes in the kit and I'd rather run a bit rich than sieze anyway.

It does power wheelies pretty easily now anyway.

There's some video of me starting the bike and taking it for a quick ride this morning and a photo of the bike in my home directory.
http://members.iinet.net.au/~nickopen/

For those interested:
Purchase price $1500
2nd hand Radiator ~$100 I think
Braided lines $160
2 new tyres fitted and balanced ~$300 I think
Dyno tune $99
Jet kit $300
brake pads $60
Total = about $2500 + many many hours. pretty good I reckon for the fun factor.

<END SNIP>

So yeah, that's about 990 british pounds if you want a conversion seeing as most are in the UK.

Mods are pretty much just a "cut" airbox and running premix. Has a rear head on the front, but only a dodgy setup with the stock hose (almost melted it on the exhaust!).
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fstnsr

 
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Sat Oct 07, 2006 7:33 pm » Post: #2 » Download Post

love the starting method Laughing
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NickoPen

 
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Sun Oct 08, 2006 9:27 am » Post: #3 » Download Post

No other comments? I guess its a long read! sorry!

Anyone care to comment on the dyno chart? I don't know if it looks good or not. The guys at the shop seemed happy with thier work though. I'd rather not lean sieze it on the first straight i get to though!
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Andy
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1991 Honda NSR250 MC21
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Sun Oct 08, 2006 2:12 pm » Post: #4 » Download Post

Why have they supplied a graph of hp vs. speed rather than RPM. It doesn't really tell you wwhat you need to know - only that peak power is just above 61hp. Knowing where you make peak is more important than knowing how much you make, if you are going to ride it fast!

The shop should have the information stored though, for future reference, so maybe you can get a new graph with the RPM e-mailed to you?

Always interested to read experiences like this though.

I'm with you too fstnsr... interesting starting method! I'm glad it didn't slip off the stand!! Smile
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NickoPen

 
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Mon Oct 09, 2006 8:37 am » Post: #5 » Download Post

I don't think they had an inductive pickup for the tacho, so they just ran the road speed as a 5th gear roll on. If you can point me to a table of gear ratios, I can work out the conversion for my sprockets.

Any ideas what the flat bit is just where the AFR starts to drop (around 130 k/hour)? Any comments on the AFR?

Oh yeah, I've been starting it like that since I got her cos there's no kick starter. You've got me worried that I'm going to knock her off the stand now! Any other suggestions that don't involve me running down pit lane pushing it?
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