Track stories 2007

[RacingJake]

A few days ago I was on ebay and saw this swingarm with less than an hour to go, so I just bid 100 thinking I'll get outbid like normal, but I didn't. I guess the Harley Gods where looking after me \\/ this swingarm is 4 incher longer than the one I have now. Should make it easier to mount the 2.5 bottle and battery once I do my hack job.

[RacingJake]

I did a little grinding today and didn't punch through the case \\/

Just got to do the bottom now. Looks like a 16F and 42R sprockets should be close to my 14/46 gearing.

That was easy, bottoms done too

[lecroy]

I did a little grinding today and didn't punch through the case \\/

What r u up 2? 750 gears?

[RacingJake]

Yeap the 750 gears are 46/99

[lecroy]

Did you have your gear changed or find a new crank?

[RacingJake]

I picked up a welded straightgear crank a few months ago and going to put my 1395 block back on with another 750 head and see how see's runs this spring. Should be in the high 5's cause the 1166 was in 6.10's.

Don't think I'll use the nos with the MTC pistons cause they seem to crack real easy ????

I'll ask Ryan what he was running when he was using the 750 ratio

[lecroy]

Sounds like your all set with it. I think you will run in the 5's without the nitrous. That 4 number is going to be a little harder to get to. I would be happy with a 5.2.

>>>Don't think I'll use the nos with the MTC pistons cause they seem to crack real easy ????

How do you figure?

[RacingJake]

I had another MTC piston crack around the skirt. I guess they don't have much alloy in them to make them stronger. They are real shinny but when compared to Wiseco piston's you can see a differance.

I like gray better

Ah you seen that other post, just thinking out loud
I think solid mid 5's are doable. Will see how this longer swingarm works out.

[lecroy]

Yes, I saw the post. I know a guy that has a very nice chassis for sale. It looked like it had never been down the track. Very good quality. It was on eBay so I'm not sure if he still has it. I thought about buying myself just to drop some weight. I could pick that bike up in the air with no problem (less motor). Something like that would put you into the 5's easy.

That is very strange about the pistons. I have never cracked a skirt in any of my bikes. Dirt street or drag. Did both crack in the same place on the skirt?

Wiseco no longer makes turbo pistons so I have been running MTC's. The skirt on the MTCs is a little shorter than the Wisecos except where the wrist pin is. The MTCs I have look much thicker and heavy duty than the Wiseco. As for the color, it's had for me to judge a difference between the two. My Wiseco parts were more than 10 years old so they may have changed something. I will post a few pictures. Do your parts look similar to mine?

Left is Wiseco, Right MTC. Keep in mind Wiseco had been ran from some time, the MTC part was out of the motor that I blew on the 3rd pass, so it's still very clean...

[lecroy]

This is a close up of the skirt and pin area.

[lecroy]

It's tough to get a good picture of metal with my camera. I was trying to show you the difference of the color from the outside. Again, MTC to right. In the picture the MTC looks a little darker, but sitting on the desk they appear about the same.

These are both turbo pistons, 1428cc. The Wiseco weighs 302/365 grams without and with wrist pin, the MTC 321 / 399g. I used the upgrade tool steel pins from MTC but now I have those APE parts that I am sure weigh a lot more.

[RacingJake]

My mtc pistons are .053 thick at the skirt and the wiseco are .093 ???

The crack is about 1/2 long and in the same area as my other piston.

Just looking at the mtc's they look just like pure aluminum but the wiseco have that flowing look of added alloy.

They are the street one's (mtc) and maybe that's my problem. Maybe I need the 13-1 drag ones ???
thanks for the pic's

[lecroy]

If I measure the two pistons from the thinest part of the skirt, the Wiseco and MTC both measure 0.090. The amount of the skirt that is that thin is not in the same for the two pistons. Looking at half of the piston, the Wiseco's skirt is 0.090 for about 3.3" where the MTC is only this thin for about 1.1".

It could be that they make them a little different for a drag motor. I wouldn't have thought so, but doesn't hurt to call them.

It seems like when I made the switch, I was talking to a few gear heads who said the MTC parts were held at a much tighter tolerance than any other piston. These were people who never worked for MTC. I really never had any problems with the Wiseco, other than they stopped making them. I have used their parts in all sorts of motors.

[lecroy]

Jake, just a little more info. I measured both the MTC and Wiseco parts for hardness. Using the Rockwell B scale and looking at an average of 4 data points on the skirt of each part. The Wiseco has a hardness of 64.8. The MTC measured 67.2.

Looking at some different kinds of aluminum, and their Rockwell B hardness:
2011-T2 B60
2024 B75
6061 B60
7075 B87

We really don't know anything about how these are processed or the kind of aluminum that was used but I think its safe to say that at least the two parts I have are very similar. Yours may indeed be cracking because of the thin wall. If you do give MTC a call, I would be interested in hearing what they have to say.

[RacingJake]

The swingarm showed up today and looks like it's going to work, WB is around 65 inches now. Looks like I'll have all sorts of room now to mount a car battery so I only need to charge it once a month.



My mtc piston showed up too and the cases are bolted together, just waiting on one more package by monday and she'll be back in the frame. With all this warm weather and the tracked closed a month early things are happening fast.

Well see how the pistons look at the end of 08