Correct solder for a YZ250X squish test?

[Tahoe Gator]

I believe I’ve read that the stock YZ250X squish is over 0.10” and so I am presuming I need a solder thicker than that. I just so happen to have the solder in the attached pic on-hand. 

It measures 0.1150” in diameter. I presume that’s baby bear: not too thin, not too thick?

I squeezed it with a wrench and while it’s certainly malleable, I wouldn’t call it “soft.” Any reason to be concerned over how easily it deforms? I don’t want to damage the piston or head. 

[YZDOC]

That's not rosen core that is softer. .093" is what you need.

 

[Tahoe Gator]

Thanks! I just ordered the correct one.

If anyone knows if new head o-rings are required for re-install, I’d appreciate knowing so I can order in advance. 

[YZDOC]

If they have been torqued down for a while, and/or run, I would order new ones.

[Danceswithtrees]

60/40 lead tin rosin or acid core solder normally in the 1/8" size.  Don't use lead free or silver solder it's too hard.

[nicad]

Not easy finding that type of Solder. All the usual suspects don't carry it.

Edit: Amazon had it, but I had to add $25 to the order for them to ship. The Dog is getting a Big Bag of Dental Chews.

Edited March 21, 2018 by nicad

[Ron W]

I would replace the copper washers under the head bolts as well. I know some people don't, but my bold ones leaked.

[Tahoe Gator]

I ordered this one from Amazon...

Alpha Fry AM22406 Cookson Elect 40/60 Acid Core Solder https://www.amazon.com/dp/B001A2WHYY/ref=cm_sw_r_cp_api_1dXSAb5YGNYD8

(didn’t need to order dog treats LOL)

[nicad]

I found the .093 as per YZ Doc's  recommendation. Hope it is thick enough. 

[Kinger317]

If it's not, you need to do something about your squish clearance!!

[kxrob]

13 hours ago, 2 STROKE YZ DOC said:

That's not rosen core that is softer. .093" is what you need.

 

So for us metric guys that is 93 thou per inch , so about 2.35mm ish or did I convert it wrong?

[numroe]

8 hours ago, kxrob said:

So for us metric guys that is 93 thou per inch , so about 2.35mm ish or did I convert it wrong?

I use 3mm soft core solder. Easy to buy at many places.  I gently turn the flywheel using a socket+wrench on the crank end nut holding the flywheel. Clockwise for the first crush, then back and forth gently. Leave the head on. Put two solder pieces in at the same time through the spark plug hole. Hold them against the cylinder bore above the wrist pin. Done it many times to measure in the 1.3 to 1.6mm range.  Be sure to make the two solder pieces long enough and with a correct pre-bend in them so easy to handle and feel them touch the bore. Get someone to help if you feel a bit uncoordinated.

[Tahoe Gator]

2 hours ago, numroe said:

I use 3mm soft core solder. Easy to buy at many places.  I gently turn the flywheel using a socket+wrench on the crank end nut holding the flywheel. Clockwise for the first crush, then back and forth gently. Leave the head on. Put two solder pieces in at the same time through the spark plug hole. Hold them against the cylinder bore above the wrist pin. Done it many times to measure in the 1.3 to 1.6mm range.  Be sure to make the two solder pieces long enough and with a correct pre-bend in them so easy to handle and feel them touch the bore. Get someone to help if you feel a bit uncoordinated.

this method seems SO MUCH easier than removing the head multiple times and laying them on the piston, not to mention reducing the risk of engine ingestion.

The key of course is making sure it touches the cylinder wall but it would seem you could feel for that.

Thanks!

[Red Lightning]

On 3/21/2018 at 10:45 AM, Tahoe Gator said:

YZ250X squish

 

Call me pathetic if you'd like but im not familiar with this term. What are you referring to when talking about squish?

[GCannon]

Read this, its long but your new understanding will be worth the work.

 

[numroe]

15 hours ago, Red Lightning said:

Call me pathetic if you'd like but im not familiar with this term. What are you referring to when talking about squish?

Don't be pathetic. ?   Go to images.google.com and search for two stroke squish.

You will find many images like this.

[GCannon]

That picture goes great with the description shown in the link

http://www.amrca.com/tech/tuners.pdf

see page 34-38

Just remember this is older research and theory and 2 stroke cooling and exhaust systems have improved significantly

[Tahoe Gator]

32 minutes ago, GCannon said:

That picture goes great with the description shown in the link

http://www.amrca.com/tech/tuners.pdf

see page 34-38

Just remember this is older research and theory and 2 stroke cooling and exhaust systems have improved significantly

very interesting read!

[nicad]

Just did the squish test on my 2017 yz250x. I must have one of those high tolerance Motors. The solder I used which was .093 did not even touch the cylinder head so I have to get some thicker stuff. The dog is enjoying her treats though..

[Tahoe Gator]

I bought this 0.125” solder on Amazon. With Prime it arrived in 2 days. It was the same as was recommended by RB Designs in their squish test instructions and confirmed over the phone as the right diameter for the “X”.