Project Yamaha SRX 250 3WP

Been a bit slack with work on the SRX lately so yesterday I got stuck in.
I needed to scrounge some bits from the head on the matching numbers engine and it was going to get the nice piston and rings from the previous rebuild as well as the head.
Stripped it down and the bore is pretty glazed and lots of muck on the piston. Stock bore as well.

A few pics from the phone with more to come later in the day.









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It would have been for sure, although I did manage to start it when I got it home originally. But it only ran for a minute or 2 so it didn’t show up.
The oils was so black with carbon and it stained everything it touched lol.
The bottom end seems to be really nice though.
It now has a nicely honed stock size barrel with new rings and a reconditioned head so it will be the fall back engine as it is the matching numbers to the frame.



I also slipped the 350 bottom end into the frame as well as putting the front wheel back on to keep it all in position.





I forgot what a tight fit they are in the frame, heavy duty bubble wrap comes in handy when protecting paint



I also re-checked the new rings for the 350 Piston and they look to have been gapped to suit the bore so I will check with the machinist this week when I drop the head in to be done.
I feel Ike I am getting somewhere now


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Yep... its almost as advanced as the Hammertone Flyer
Anyhoo... I did some tidying up on the wiring loom last night.. re-wrapped a section and then put some split mesh over it.. then had a look at which Ignition switch would work... and there is an issue.
The original SRX250 51Y has an ignition switch with 4 wires coming out.. just the same as the FZR250. The SRX250 3WP however has only 2 wires from the ignition.. with a completely different connection (obviously).
I have 4 ignition switches in total.. an aftermarket unit with 4 wires, a 51Y and FZR unit each with 4 wires all colour coded the same and the last is from an SRX600 that has 2 leads.. 1 with 2 wires and the correct connector and the other with 5 wires.. so none of them will do the trick.. grrrr. now to look on Zenmarket for a 3WP ignition switch...

 

Possibly, or I might have 2 SRX250 switches, I will check tomorrow.



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I have had a look at all 3 switches and I might open up the SRX600 unit and see if I can de-solder the extra leads... They are redundant for my loom so rather than having a spare plug hanging around If I can remove them and maintain the function of the correct plug that will save me some $$ and leave me with the same keyset for ignition, tank, seat and helmet holder.
Out to the garage for some fun with an ignition switch tonight I think.

 

OK.. I have opened 2 of the switches up and the number of connections on the SRX600 item are interesting.. the FZR / SRX unit is far simpler.
I am thinking I will de-solder the un-wanted wires from the FZR / SRX unit and try to unclip the tangs on the Red socket from the SRX600 and the 2 main wires on the other one.. they should then slip into the red socket.
Or I could just de-solder it from one and solder it onto the other one.. simples...

At least it will save a few shekels to go towards the rebuilt head.. dropped it off today.

 

So... I am pretty sure my little experiment was successful.. I took the 2 main ignition wires (red and brown) out of the 4 pin socket and then dug out the trusty Tradeflame gas soldering iron and gently de-soldered the other 2 cables from the switch base.
I stripped off the hard heat shrink and put on some new Soft heat shrink.. I didnt have enough Black so I did the middle part red.. just for giggles
I then slipped some mesh expandable sheath over the top and I will tape the ends tomorrow.. lightly grease the lock and slide then reassemble and test it with the multimeter against one of the others.
Looks like I saved myself between $75 and $90 by doing this and it has kept the keys all the same.

 

A few other things happened this week... I dropped my Cylinder head in to have the valves re-ground and the head assembled with correct clearances etc. That should take around a week or 2 with Easter in the mix.
I have been thinking long and hard about the clutch on this thing.. I am sceptical if the standard 250 clutch will live with the bored 350 with bigger cams so I have sourced a TT350 clutch from Toowoomba.. and once I have that I can well and truely button up the bottom end of the motor.

I also dropped my seat off to be recovered and the foam fixed up. It isnt the sort of seat that can be recovered at home.. unless you have an industrial sewing machine and are good at that stuff.. plus I started looking at identifying where everything goes on the wiring harness.. as I bought the harness from Japan (3WP harness) it was some trial and error finding what went where and what is different to the gear I have.

The main differences are the TCI unit.. timing etc is the same but the 3WP unit has a different lead setup and there wasnt enough existing to change around to suit so another TCI is under way... as are the left and right switch blocks.. I was going to use the FZR items but the connections are vastly different... so 3 items on their way from Japan in the next week.. then to repaint and recondition the switch blocks.
The only other item that is different is the pick up lead. I just need to change it over to 3 bullet connectors.. I know the details are in the forum somewhere about the correct Japanese Bullet connectors.. I just need to try and find it lol

I have also been thinking about the standard foot-peg brackets and polishing them.. I think I am going to get them Powder Coated.. for better wear capability.. most likely a Satin Finish Gunmetal... which will be the same colour I do the top bridge.

I dont think I will ever try and convert a bike to a later model of itself again...lol too may dramas to make it all correct

Hopefully I will get plenty done over the long weekend...

 

I didn’t end up getting as much done toy as I wanted as some yard work was required.
Started loosely securing the harness into final position, at least over the front half of the frame. I need the Airbox in to finalize the rest and that goes in after the carbides are on.

Last thing today was to clean down, mask up and then paint the front brake discs.
What a right pain in the rear to mask up they were too.
Done now though, couple more light coats tomorrow and they are done.






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Hmmm after spending countless hours searching for reasonably priced front disc rotors and then deciding to use my existing items.. cleaned sanded and painted I find a set of front brake rotors... grrr
Now they are wave design that I dont normally like but... they have T6160 centres and dont look too bad. I am not sure on my used front discs.. I know they are getting close to the wear limit but no idea if they are true.
For the sake of A$200 I am seriously thinking of getting these ones.
https://www.ebay.com.au/itm/For-Yam...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

 

Thanks for the input Blair.. it was an easy choice when I couldnt find any.. other than the A$250 each EBC items from the UK lol
I have to change out the rear as it was undersize and badly scored.
Probably will stay with my existing ones for now.. I have heard horror stories about Chinese SS discs..