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Author Topic: Yet another SR250 Tracker UK Build  (Read 12878 times)

Offline JadusMotorcycleParts

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    • Jadus Motorcycle Parts
Re: Yet another SR250 Tracker UK Build
« Reply #70 on: Jan 22, 2018, 01:21:11 »
Did you figure the ring issue out?  Could it be that you have received a ring set for the US version SR250?  That was a true 249cc engine - with a 75mm bore rather than the 73.5mm bore that gives 239cc.

Offline vortexracing

  • Posts: 48
Re: Yet another SR250 Tracker UK Build
« Reply #71 on: Jan 22, 2018, 15:23:17 »
That could be the case, I was going to rebuild it with the old rings, but the top ring has lost its marking so I donít know which way round it goes. 🙄

Having had a close look at it it seems to have the same tiny chamfer on the lower and upper surfaces.

Do you think it will go in either way?

The other option is to just buy a new set and fit them, and this time hope they are the right ones. 🙄.

I may be in touch for a header and front mudguard soon. Just one question, can you have the headers made to a different pattern ie for a high mounted exhaust or do you only do them as pictured on your site?

Cheers

Dave

Offline der_nanno

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Re: Yet another SR250 Tracker UK Build
« Reply #72 on: Jan 23, 2018, 04:16:14 »
Hi Dave,

with regards to the ring: Yes one can regap them to size, but only if it's out by let's say 0.25mm or so and even that's a I am in the middle of the Sahara and need to get home to work on Monday sort of fix/bodge. The reason for that is, otherwise they will only touch the cylinder wall in two or three points and not seal properly as they are no longer round. (For those in the know: Yes, this is an oversimplification, but it helps understanding - strictly speaking neither the piston nor the rings are round, only the bore is...) So unfortunately you'll have to get the right rings for your cylinder-diameter.

The second thing: Please grease (any old grease will do, I use normal bearing grease as I have that standing around in big 1kg-jugs) up your cylinder base gasket (and all other paper gaskets on sidecovers etc., but not the headgasket), as that will make removal a lot easier and in terms of the sidecover gaskets, i.e. gaskets that won't get as hot, you stand a very nice chance of the covers being removable without destroying the gasket in the process AND sealing nicely.

Oh and aside from my other comments: Nice build, I am more and more inclined to really build a SR250 myself sooner or later. Lots of tuning potential in that engine.

Cheers,
Greg
« Last Edit: Jan 23, 2018, 04:22:33 by der_nanno »
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Offline vortexracing

  • Posts: 48
Re: Yet another SR250 Tracker UK Build
« Reply #73 on: Jan 24, 2018, 17:40:59 »
I think it's easier to order some new rings so that's what I'll do, at least when I button it all up it should be sorted.

The good news is I got the top yolk assembly back from aqua blasting, all bolts , nuts etc re-plated. Graham is just going to do the controls as I am having them raw alloy as well, I'll post some piccies up when I get them back.


Untitled by eastham_david, on Flickr

Offline JadusMotorcycleParts

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Re: Yet another SR250 Tracker UK Build
« Reply #74 on: Jan 24, 2018, 22:15:54 »
Damn, that looks great man.  Nice to go all in with replating the fastenings as well.

I agree with Greg, if you trim and force those rings, they will essentially be out of round.  Best try with a new set.

Offline vortexracing

  • Posts: 48
Re: Yet another SR250 Tracker UK Build
« Reply #75 on: Jan 28, 2018, 17:02:09 »
New Yamaha piston rings on their way from Bulgaria   ::)

Not a great deal done this weekend, the loom has been cleaned with IPA and a lot of elbow grease (plus the aid of a toothbrush).

Change of heart on the build this morning though, I'm removing the side panels and going for an open triangle with a 4 cell anti gravity battery under the seat.

I am looking to remove around 10kg from the bike. I spent 1/2 hour weighing stuff from the original build and it's amazing the weight that can be lost. A 4 cell Li-on battery,  plus aluminium fenders and other stuff removed or replaced, i.e. indicators, headlamp and centre stand, I will easily remove 10kg and that's before considering aluminium rims for the wheels. So target is around 110kg and 24BHP. All that should make it quite sprightly I think.   :)

Here is how the loom looked before

P1050479 by eastham_david, on Flickr

P1050485 by eastham_david, on Flickr

but it now looks like this


Untitled by eastham_david, on Flickr

by eastham_david, on Flickr

by eastham_david, on Flickr

Offline vortexracing

  • Posts: 48
Re: Yet another SR250 Tracker UK Build
« Reply #76 on: Feb 18, 2018, 16:46:16 »
Not as much done as I thought I would get done with a few days off work, mainly due the Mrs Having decorating plans for me ::)

However I managed to source some hand rolled mudguards made to my dimensions for a bargain of £50 plus postage for both front and rear !!!!

Also sourced some tabs from eBay for attaching the battery tray and mudguard, they are the ones used to fasten Kart floor trays to the chassis rails, all for the princely sum of £5

New Hagons shock at +20mm e2e length also arrived, and a 4 cell Anti-gravity battery.


So it was fitting the rear of these and working out how to fit the 4 cell anti gravity battery to keep a clean open frame triangle.


so here are some photos

Don't take notice of the black and bare guards, I am still debating about having them black or leaving them a polished alloy.

Untitled by eastham_david, on Flickr

Aqua blasted top yolk and the bars fitted.

Untitled by eastham_david, on Flickr

Untitled by eastham_david, on Flickr

The good thing about lifting the rear of the tank by adding extenders to the standard tank mount was that it now leaves room for the Starter solenoid, which was deeper than the battery!!!  :-)


Untitled by eastham_david, on Flickr

Untitled by eastham_david, on Flickr

The battery is tiny  !!!!!

Next job is the get the battery tray cut out of alluminium and some tags welded on the locate the battery and sit the starter solenoid holder onto.

Oh and when the voltage regulater is back from the aqua blasters, I need to fit that, I think thats going to have to go under the battery tray, which is shame as it will be seen through the open triangle, but it needs to be in the airflow.


Untitled by eastham_david, on Flickr

Untitled by eastham_david, on Flickr
« Last Edit: Feb 18, 2018, 16:49:24 by vortexracing »