Project Yamaha SRX 250 3WP

Well, a replacement, replacement head arrived today... Turns out the original replacement head was for an SRX250, easy mistake to make and no harm done so I managed to source a TT350 head with the correct cam caps, valves and buckets.
It is pretty grotty so I will clean it all up over the weekend and send it off for vapour blasting.
I have also decided I want to paint the engine Satin Black rather then the Silvery colour so there will be lots of maskingetc as it will also be given a few coats of Satin 2K clear.
May as well do it while the engine is out... lol

 

I managed to find the time today to strip down the new (old) head ready for Vapour Blasting.
Typically my valve spring compressor was in the 3rd (and last) of the plastic crates marked tools.
I was suprised that the inlet valves seemed to have a good clean face both on the valves and the seat.
The exhaust wasnt burnt and the face was clean, just not as good as the inlet.
Like most TT / XT 350 Yamaha's the combustion chamber show some signs of a minor failure... nothing dramatic though.. it might get some smoothing out after the vapour blast... the inlte and exhaust will also get a little bit of work, just to port match the inlets and take out the casting dags in the enhaust.
Other than that it was pretty much as expected.


Inlet valve


Close up Inlet Valve


Close up of Exhaust Valve











Ready for Vapour Blasting



And this lost for plating.

 

I started doing some prep for when I re-paint the engine and noticed the Stator wires have suffered a bit over the years. Insulation has gone hard and cracked at a stress point.. so looks like I am going to pull the stator out and try to replace the cables... better now than finding I have a dead short when it actually runs (or is that when it eventually runs).


Looks like I also need to repair the trigger wires as well.. they also have broken insulation.
The joys of old (40 years old) motorcycles.

 

No mate...nothing that even slightly resembles fibreglass sheathing or silicon wires etc... no high temps involved with bore pumps lol.
I will have a look at what is on the matching numbers engine and make a call based on that.

 

Haha, I have a customer in Albury who is a motor rewinder but he probably won’t help me as I have just denied him warranty. He seems to believe a bore pump motor should have a 4 year warranty. 2 years is our standard so just slightly out of date lol
I found some Silicone coated fiberglass sleeve on the bay of fleas. I just need to measure to get the right size.
Maybe tonight.
My vapor blasting and plating is ready so will pick it up this afternoon.


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This is the stuff I am thinking of getting...
https://www.ebay.com.au/itm/176545519490?var=476160602798

 

Happy with my plating that I got back today.
These were items I had wanted to do myself but by the time I bought more plating solution this way was easier. Great finish as well.



Happy with the vapor blasting as well.
Some cleanup to do on the inlet and exhaust ports just to smooth out the casting dags.


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There isnt a lot to smooth out on this head... I am not going to worry about the combustion chamber, it will be fine and really there isnt much to clean up on the inlet or exhaust ports either... probably a lot of work for negligable gain.






I should get to pull the old head down this weekend.
Clean up these seats, lap in the valves from the old head (valves and seats ground in Sydney) and then reassemble to check valve clearances... I will no doubt need some shims.

 

Hmm turns out fixing the Generator wires etc isnt quite as easy as I thought.
The Generator wires will be OK, they need to be soldered and then have heat shringk over them... then wrapped.
Hopefully that will work out fine.
The spark trigger is a different matter. the wires were brittle and weak on the outside of the rubber grommet but they were also moulded into the grommet.
I had to slice open the grommet to remove the wires, I have stripped them and will solder and heat shrink, them slide them back into the grommet and seal it up. I will need to get some heat and oil resistant Sikaflex for that.
Oh the joys of it all..

 

Well, a repair has been effected and while it isnt pretty (it is hidden so doesnt need to be pretty) it is effective. Each line has been tested and reads ok on the multimeter.


Some heat shrink and then a vintage material wrap should protect is for a few more years.
The replacement head has had the seats cleaned up with a little 3 angle job. I am torn between the valves that came out of the leaky head and the originals from the replacement. The valves out of the leaky head have been ground with really nice faces (even as well) where the others vary a little and would only get lapped in.
The leaky head had the seats cut in a bit further and the valves from that one are all approx .3 to .5mm shorter (top ground to suit available shims) so I will probably have to assemble with both sets to see what the clearances are and then determine the best route... Its a good thing it is only a single cylinder, an FZR would be 4 times the effort lol.
I still need to finish sanding / roughing the engine ready for primer and then Black paint.
So more to installments to come

 

Job for today was to finish cleaning and prepping (removing a lot of the original paint I applied) the engine. Then masking everything up that didnt need painting.
I am using a new paint from Supercheap... MTN Engine paint... they only had Gloss Black, its it a really nice paint to use.
I am not sure if I want to keep it Gloss Black or go Satin... either way it is getting 2K clear.

 

A few more pics

The Valve cover is painted the same colour as the Tank..... Spilt Blood Candy.
Hopefully my Clear coat will arrive during the week allowing me to finish the painting and then get the head assembled, valve clearances set and then back on the engine ready for installation back in the frame.

 

I had a bit of a test tonight using my Satin finish clear coat... for 2 reasons.
1 to make sure it didnt fry up going over the engine paint and 2 to determine if I actually liked the Satin finish.
Results were it didnt fry up.... this is good.
Finish wasnt what I was looking for so I am going to leave it Gloss. I will most likely put a gloss clear over it all as I want to paint the Yamaha in red on the clutch cover and I have the valve cover to clear as well.
So now next cab off the rank is to lap the valves clean it all up inside and then assemble the head to check valve clearances so I can get the required shims if needed.
Note to self... buy some valve stem seals...

 

Parts ordered today.... Valve stem seals, exhaust gaskets, new copper washers for the oil line and 1 Valve spring seat... yep.
Some how there was a rogue washer inserted under a valve spring instead of the formed seat.. .there was a difference in the thichness of the washer and the seat and it also meant the inner valve spring wasnt seated properly...
I dont know what difference the seat pressure would have been but at least now they will all be the same...or as close as possible.
I fiddled about on the weekend taking about 4 hours swapping between different valve buckets and shims (lucky I had quite a few) to eventually get to within .01mm of the largest clearance for the valves.
I was pretty impressed to have been able to do that without having to buy any more shims.
Now I just have to wait for the parts to come into Albury from Yamaha....
Getting there... slowly

 

Parts arrived in 2 days from my Yamaha Dealer much to my surprise.
Yesterday I started to lap the valves in, each one done, cleaned up and then assembled back into the head to ensure I didnt mix up any buckets or shims. I then rechecked the clearance on each one after assemble... just to be sure and all was good.
I have in the past had issues installing stem seals so I used an old valve (I have a few of those) with an 8mm 3/8 socket and then the stem seal and used that to pop the seals on nice and straight.... they go on with a satisfying pop.
Probably not the first time this has been done but far better than spending $50 on a motion pro tool that I would most likely never use again lol.
Once the head was done it was back onto the barrel, torqued down and then in go the cams. Amazingly I got the timing absoluetly spot on first go... would her over multiple times to just make sure and every second turn the marks lined up on TDC
Cam cover on, oil feed line on, ready for the YAMAHA lettering on the clutch cover to be done... I am going to use a spare (scrap) clutch cover (I knew it would come in handy at some stage) to get my process down... I will be using a chisel point paint pen... it isnt easy for an elderly person with poor eyesight and unsteady hands to do... its even more difficult for me.

 

Finished the lettering. Now to clear coat it. Not today though.



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Clear is done... engine is off the makeshift stand and waiting to go back into the bike... There is still a bit to do to clean up the frame. some paint touch ups and maybe even more clear coat.
The frame wasn't hit with clear originally when I painted it and while it come up ok with a bit of a clean I may just stip it all down and hit it with some clear. With the engine out it wont take much to get it back to just the frame.... decisions, decisions lol.

The engine is now nice and glossy.

 

Managed to get a little bit more done last weekend and during the week (a few hours after work over a night or 2).
Frame has been de-dusted and cleaned, then clear coated (2K satin). The swing arm has copped a bit of a hiding paint wise so it came out and was rubbed back, feathered and re-sprayed the same colour... then hit with 2 coats of 2K sating clear as well.
All reassembled and then slipped the engine in... plenty of buble wrap to protect the down tubes and engine.
All bolted back up and torqued up as per the manual.
Still trying to sort out the mounts for the Oil Cooler. I have one of the special P Clips that mount it to the frame and half of the other. some light fabrication is required to make the other half. Then I can finish the plumbing, connect all the wiring again etc.
I like how it looks in gloss black. It will be better when the tank is painted... It will be the same colour as the Cam cover... "Spilt Blood Candy"
That is my Easter plan... painting