gpx/gt half breed project

[Gil Gallad]

i started with this: a 1990 gpx kawasaki rolling chassis and intending to either put my newly built gt350 [347cc] suzuki engine in it or a gt250 engine. mind not fully made up yet  rolling chassis cost me next to nothing and came as you see it, plus seat and tank. the idea was to build a gt with modern suspension and brakes, and this came up. atm, i'm building an engine cradle for it. when it's all welded up i'll post another piccy.
cheers, gil.


photo of the gt350 engine - note 4mm base plate under barrels. this is when it was in a gt frame.

[Gil Gallad]

piccy of the frame, with new cradle and new powdercoating  ;D
cheers, gil.

[Gil Gallad]

this is where i am now with my genuine shed build. spannys off for coating, but she's coming on slowly but surely. all electrics done, just needs the stainless banjo bolt - on order - and i can sort the rear brake with its all new innards. front already done  8)
cheers, gil.

[m in sc]

thats an awesome build. did the jack plate go on with porting as well, or did you just Jack the cyls and cut the deck.?

that frame looks great, very very well done. 

[Hardy]

I think you have done a wonderful job with the frame, I had to look twice to check it wasn't factory!!

Good luck with the build.

[EE]

Really nice frame work looks very factory.. nice..

[idr5c]

Like the bike and the coffee cup 

[Gil Gallad]

many thanks for the thumbs up, much appreciated  ;D
to answer a couple of questions: when i took the barrels in to be resleeved at 64mm, i told the lad at S.E.P. what i was doing and told him roughly what i wanted, and there would be a 4mm base plate, so to port it accordingly. he also did a mild porting tune - didn't want anything radical at this time. the only thing i had to do when i got the barrels back was to mill 1mm off the step inside the bottom crankcase, where the bottom of the barrels sit - as the pistons were hitting it [just]. and mill a 3mm deep half moon piece out of the back of the pistons, as they weren't quite uncovering enough of the inlet ports. i then put a base gasket on the top crankcase and noticed the transfer ports had so much extra metal on them, they were way off the transfer port cutout on the barrels - so that all came off and was smoothed out. why suzuki did this is beyond me, it can't have done anything positive for the gt ramair engine. done now and happy with it. fitted gt250a 28mm carbs and jetted it as if it was an rd350  ;D fitted my own electronic ignition and an old pair of spannys and - i couldn't even kick it over, even with 0.7mm copper head gaskets. so, sent the heads off to a bloke who knew exactly what he was doing and he widened the heads out to 65mm, took the original squish band down 1mm and smoothed that up to the edge, where it was 1mm deep. then removed metal from the dome - 2mm if i remember rightly and sent them back. i measured the volume of the first heads i had done [badly] and the compression was about 22/1, so just a tad high. i measured the volume of the newly milled heads and the c/r was about half that. made some 0.3mm copper head gaskets and fitted it all again. second jump on the kickstart and away she went 
not the easiest thing i've ever done, but certainly not the hardest.
cheers, gil.

[Gil Gallad]

oops, due the the first ever gt250 oilpump failure i've ever known, this happened. not quite back to the drawing board, now i've found out what the problem is, but a complete stripdown and rebuild. as arnie said "i'll be back" 
cheers, gil.

[NoRiders]

Hey Gil, that's one hell of a good job on the frame, as has been stated it looks factory fresh. Your engine modifications are truly mad...love it :)
So, did the engine give out during bench running-in or was the bike now running on the road when it happened? Either way....best of British to ya.

[Gil Gallad]

i found the piston problem quite by accident. 1. i had a slight weep on the oilpump which i couldn't find, so i changed the oilpump and lines. 2. changed the engine over to the gpx chassis after the dickhead that was supposedly paying me to build a gt350 pulled out. 3. i got a tiny weep from the bottom crankcase, again i couldn't fix it, so i changed the crankcase. 4. i stripped the engine and found the piston damage. 5. i rebuilt the engine after testing the pump and lines - they were kaput. 6. ran the engine for about an hour, then stripped it again - all good. 7. took my new crank into shop as one of the middle seals had collapsed = another story, but the plan is to put the re-rebuilt crank in the 350. so there ya go, all up to speed. quite pleased with the frame as every bend and all the welding was done by eye - and a pipe bender and welder of course. it looked right to me, so that's how it was built  ;D after 6 weeks the crank is finally done, just in time for the coldest it's been round here for years 
cheers, gil.

[Gil Gallad]

engine now running perfectly and waiting for a hand from number 3 son to get her out of the shed - i don't want to scratch her and there isn't much room in here. excuse the snapped off rear indicator - that's the third one i've broken. it's where i shove my knee under there to hump her back over to the right. second photo shows the new GTX350 decal in gt250 glitter orange. still waiting on the fuel tank decals - he made a mistake, so he's doing them again, hopefully correct this time  8)
cheers, gil.

shed build mongrel, nearly there:


GTX350 decal:

[85RZwade]

Wow, it's turned out really well! That bike is going to be a lot of fun 

[OnlyCrimnson]

Bravo, very impressive!

[Gil Gallad]

many thanks for the thumbs ups  8)
if it ever stops raining in this god forsaken country of ours i'll get her outside for a proper blast. still waiting on the fuel tank decals, but apart from that she's finished. now then, what can i try next? the ramair gt250 reed conversion is now running, so i'm on the lookout for the next project  ;D
cheers, gil.