suzuki gp100 tuning

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Ive a GP100 which i am restoring, its on the road and im looking for a expansion chamber
exhaust, i know the microns are well rare to find, do you know of any other expansion chamber which can be easily modified to fit, ive got another carb which has a ledair kit
fitted to it also ive the 102.5 main jet for my existing carb to try, i did try the ledair
jetted carb went well midrange but over fueled top end, so anyone wants to sell a micron
please let me know, if i cant find an expansion i will look for a new old stock exhaust,
just got some nos folk tubes! Feel free to join my FaceBook GP100 page


Hi Midge
I do remember that GP100 on ebay i did phone the chap and offer to buy his micron,
the bike did look good in the pics.
I bought mine for £175 non runner 2 owners, cleaned out the tank and carb, it had
already had a top end rebuild and lots of receipts and history, original warranty
book and tool kit, got 2 Metzler ME22 tyres fitted, (£27 each mmm) general service
and clean up, went straight through the mot, bought a dial gauge to do the timing,
just fitted new rear mudguard and shocks, i will do the folks over the winter,
ive done 800 miles on it in 2 months, starts first kick, as i weigh over 14 stone
and am 6ft4 did drop a tooth to 14 on the front sprocket, it did struggle on going up slopes
and headwinds in 5th gear with the 15 tooth, but now i can cruise at 55mph almost everywhere. I did have one of these back in 82 when i was 17, ported it and had a micron on it, good fun. I this one putoline ttx but am changing to MOTUL 710 because of the better smell.

Hello Mudguts,Well the bike is now up and running very well, i have been thinking of dropping the front sprocket on mine down to a 14 aswell. My only concern is how much top end you loose on it! As i am 16 stone..Have had to do quite alot on the bike I.E new tyres replaced both front and rear mudguards brake cable on front have used a YB100 front cable as they are 6mm opposed to the 5mm standard thickness..And fully serviced it...Am still trying to find a complete toolkit for it..... Then hopefully over the winter would like to do some engine tuning really to get abit more power from it if possible...I the same as you remember when these with the Micron and engine work really did perform very well...Now i have a hope to actually take my Motorcycle test on this bike next year...

Hi midge
With a 14 front sprocket, it will cruise at about 55 at 7k, and do about 65 round about max
kindest revs, i think the trade off is worth it with us being not as small in frame
as a 17y old. When i was 17 with mild porting, micron it would pull a genuine 78mph,
it would rev nearly out of the red, a 16t sprocket did help, but be warned tuning did
loose some power from the bottom and midrange, i think that also the 14t makes for a more relaxing ride as you dont have to keep changing up and down so much,

Hello Mudguts....Thats exactly my point,it's all about about finding the balance really as you like i want it to be a nice ride and not screaming the main bearings out of it...I do like the bike and its looking really smart now (still kept the topbox on it though) its some where useful to put some waterproofs or crash helmet..I will change it to a 14 and try it really.As i wont know unless i try it..I brought this bike mainly because of the condition really and the fact it had a brand new Micron which i have had people offer £150 on its own,But where do you find another as they are really difficult to find...

Right guys, gp100 update on my minter, went to mot last week on it freshly restored and proud as punch, got 10 miles down the road on the way to the mot station and all sorts of nasty noises, pulled in and stopped and the rear wheel was locking with the clutch in in second gear!!!! caled the mot station and they sent a van out to collect me and take me home , got home and stripped the engine out straight away and split the casings to find that 2nd gear had welded itself the the layshaft, got all new gears and casings now , but also ive bought a gp125 complete engine so going to convert her to a 125 whilst at it now, Moral of the story !!!!!!!!!! inspect your gear oil level after a restoration , as mine had 1/2 pint in there max and i forgot to change it and re-fill with new oil to the max, now its cost me an engine, gutted, cheers jon

Hello Jon...Sorry to hear about the engine problem,Hope you get it through the M.o,t test soon!! Going back to my bike it is the GP100UD model and as a result is fitted with the 105 main jet Which is how Haynes list it in the manual and also the genuine suzuki workshop manual. Have dropped it down to a 102 main and seems to run better on that with good throttle response through the rev range..Have learn't quite abit about the bike over the past week or so..A few little bits to finish off..But as the weather over this way has been hopeless the past week i have managed to get alot done on it.....Hope to hear how the 125 conversion goes on your bike soon...To be honest is there much difference performance wise between the 100 and 125? Good luck speak to you again soon.....Stuart

Hi Stuart
I managed to find a New Giannelli Expansion chamber for my GP100, got it off ebay
a real bargain! It fitted like a glove! I did try the 102.5 main jet and a 105 main jet,
it runs better on the 105, the plug just the right colour, power in the midrange is
much better, and with the 14t front sprocket it pulls max revs in 5th quite quickly
(65mph). I could put the standard 15t back but at 14stone and over 6ft i think
this is about the right combination for around town riding. Ive put a clip of the pipe
on youtube just look for suzuki gp100 giannelli. I have not put the carb on with the
jet kit fitted to it as its running just fine for now, (if i need to go quicker i can always
go for a blast on my R1). Ive started a Facebook page for the Suzuki GP100,
feel free to join and share your GP100 pics.

Hi for all your port work give me a call on 07802 896103CheersMick Abbey

Just thinking on the idea of changing my GP100 wheels from spoked to mag wheels..And can't remember which wheels fit, i think there a couple of options.Any body know? i know i will have to change the forks over to disc brake aswell..As trying to find a really nice set of spoke wheels has become a nightmare..But all good fun though..Also anybody know who made the front fairing for the GP or where you can get them from..Cheers Stuart

well well well, !! i have a set of good mag wheels here that i was going to reto fit to my gt185, but i am sticking with laced wheels for the resto, i also think i may have a fork leg and a brake master cylinder aswell, tbh everything you,ll need to swap over, here,s mine all done

cheers jon

Hello Jon..Just took at a look at your bike on You Tube fair play it looks very very smart!!So are the wheels that you have the same as fitted to your GP ? and you say you have all the other bits aswell I.E forks, brake disc, wheels master what would you want for them? what are the wheels you have off,Is it the Suzuki X1 or X7 or original GP100  wheels..How well does the bike run being the 125 engine fitted? Thanks Stuart

stuart, i have from memory a pair of mag suzuki wheels from a gt185 (the same as fitted to the x5) which in turn was the same as fitted to the x1 and all small suzuki,s, so yes they,ll fit straight on, they come with the disc as well, i also have a caliper here to fit, master cylinder, you might need a speedo drive gear but i may have one, the fork i have is the one needed with the lugs cast in them to accept the disc, its a simple swap but you will have to strip one fork leg apart to change the fork lowers over, other than that its easy, and beleive me , one hell of a difference in braking power....worlds apart ! all parts are in ready to fit condition as they were going on to my gp125 but i bought a complete donor bike and changed my drums etc over to that and sold it again, hence no longer needing these, £150 plus p&p stuart... oh and the 125 conversion !! well worth it as i,m on the heavy side but if your light then dont bother, cheers jon

hi,first time so please be gentle.Doing a gp100 for my partner [she had one when she was 18] bought it off, rode it 50mils home then found it had no gearbox oil in it, seller disguising blown c,shaft seals.Offered 125 motor 15mins after completing rebuild, rebored it etc runs perfect until 15-20mils then starts chugging until it stops. Give it 2mins starts and runs  for 1mil and then repeats all the way home [no, not tank vent hole] please help iam losing hair and i have precious little to lose!

Hi, I'm new.does anyone know what happened to the performance bikes project suzuki GP100 +

I am currently restoring a blue 1984 GP100 and am trying to find the original paint code for it.  I would greatly appreciate any help finding it as I am eager to get the paintwork finished?


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