102 experts: need assistance

[blueskyracer]

We have two 102's that we run against each other in the 20SSH and CSH class and one is so much stronger than the other. I always said it was the driver but I ran both the other day and what a difference. Since these are stock classes I am under the impression that no modifications can be done to the engine except blueprinting the foot and changing the shaft size to match our props. I was told when I bought these that one had been gone thru by TJ? It is a rocket and we were just wondering why. It has the same get up and go with or without the restricter plate. Does anyone know what gives?

Second question is does anyone make a tack for these engines? We are working with Dewald to come up with an even better prop and he say he can dial us in if we can tell him our top end RPM. Suggestions?

We want to go to Nationals in Moses Lake in mid Setember and want to be ready for those west coast guys if that is possible.

[Steve Johnson]

Strong motor

I'm no expert , but straight bores , good compression, and PERFECT optimazation for the air density are all factors. Read your plugs and adjust for each day. Get yourself an air density gage( pegasus racing). Dial your carb in and read the air density. Write it all down so you can duplicate for like conditions. Compression test your engines against each other. If one is weak... send to___________for freshing up. Tj does my work and I'm very happy to have him do it. others are out there as well. Have fun. Engine tuning is a big part of this game.

[seanp3]

Mike

Not sure what to tell you about your motors. The weaker just might need to be freshened up. If you think it might be in the carburation is to swap carbs from one motor to the other and see if you notice any difference.

As far as tach's go I've used a Digatron tach which has worked well for me. They are located in the Spokane area. I've been happy with their product and service. You can find out info from them here.....http://www.digatronusa.com/

There have been several threads regarding tach's also. Just do a seach and you should be able to find a lot of information

https://hydroracer.net/forums/showthr...highlight=tach

https://hydroracer.net/forums/showthr...highlight=tach

https://hydroracer.net/forums/showthr...highlight=tach

[blueskyracer]

I am waiting to hear back from digitron about a tack. We will get that and play with props for the rest of this year which is disappearing fast. It was 39 degrees here this morning.

This winter we will go for getting the back up motor freshened up. Two more questions. What should compression be and how do you set the timing.

In this sport one thing always leads to another. LOL You first learn how to drive a little and then you want to go faster.

[seanp3]

I am waiting to hear back from digitron about a tack. We will get that and play with props for the rest of this year which is disappearing fast. It was 39 degrees here this morning.

This winter we will go for getting the back up motor freshened up. Two more questions. What should compression be and how do you set the timing.

In this sport one thing always leads to another. LOL You first learn how to drive a little and then you want to go faster.

Your timing could be a big factor on the slow motor. I just assumed you had it timed properly. You will need two tools: a dial indicator and a buzz box. The best thing to do is to have someone show you how to do it. It is fairly simple, but may be confusing to try and explain how to do it in words. I'm sure most of the other guys you're racing with using the 102 (or Y80) will show you how. For the 102 most guys will set the timing around .230" to .240" BTDC.

A good compression will be between 120 to 135 lbs. Once it starts to fall below 120 lbs it might be time for new rings.

[Al Peffley]

Blue Printing & Such

A few things to consider:

(1) The one motor may be machined and set up to the edge of the specs and the other motor may be bone stock. I am assuming that TJ blue-printed the fast engine.

(2) Check your intake ports on both engines. Some of the factory motors were/are out of spec. Check both carbs for float level and cleanliness.

(3) Your points and condensors may need to be changed, and your coils on the one motor may be weak. Find a marine mechanic in your area with a coil test machine to test the coils output. Replace weak coils if possible (they are getting harder to find. I prefer Kawasaki points over the stock points for stronger spring action.

(4) Sean is right, if the compression is lower on the weak motor replace the rings and check the pistons and cylinder walls for melted surface areas (most Yamatos will run after they stick, but not well.) Having the crankshaft trued and "silvered" will give you a much stronger and smoother running motor (part of blue-printing).

(5) Rick Montoya has Yamato 102 Owners Manuals for sale. Invest in one if he still sells them and it will tell you al the specs you need to know.

I have used a Digitron tack for over ten years with no problems whatsoever. They make a good product. There are gokart instrumentation manufacturers that make mutiple readout units for tach RPM, head temp, and GPS speed readings that you can download to a PC laptop. Tinytach is also a nice unit for a cheap price if your budget is tight.

Al

[mac19f]

102 points

What Kawasaki points do you run in the 102?

[Al Peffley]

Kawasaki Points

Sorry this took so long. Too many things going at once. Points part number is 21008-028. Few motorcycle dealers will have these points. Order them from the central Kawasaki midwest parts warehouse through a local Kawasaki motorcycle dealer. I order six sets at a time...

Al
R-25

[TONY TRUJILLO r11]

102 ?

hey mike who did you purchase the faster of the two 102 's from was it from northern california ?

[blueskyracer]

Thanks for all of the replys. We found out one of the problems this weekend. The motor went to running on one cylinder and we found a broken coil wire. In the process we had someone set the timing and that also helped but the points are worn out. Unfortunately Ric M is out of points so we will run what we have and get the rest corrected for next year. We only have Moses Nationals left. But we may see about locating some of those Kawaski points.

We were also allowed to use a different prop and it helped a ton. Now that we are on two cylinders again and a hot prop we will see what happens. This off season I plan to dig into one of these engines and see what makes them tick. I think that will help.

[blueskyracer]

hey mike who did you purchase the faster of the two 102 's from was it from northern california ?

Got both motors from Gary Lewis in southern California