Top End Job

[tz375]

Something is either wrong with the technique or the gauges. If they were HF gauges, they can probably be thrown away. If the gauges are known to be good and have been tested on another engine - any engine, then it's technique.

How many times did you kick and were the throttles wide open for all the kicks? With each kick, pressure rises until it holds steady - maybe 6 - 10 kicks or a decent burst on the button.

[Col90]

I have a harbor freight gauge that I own and one that I rented from pep boys. The harbor freight one reads 60 across all three(same as before) and the pep boys one reads 40-40-60(same as before). I am starting to believe that these gauges are not sitting right in the spark plug holes. I should also note that I tried adding some oil to one cylinder only to have a minor boost in pressure for one attempt then it was right back where it was. I was thinking dome Teflon tape might help if the threads aren't properly sealing it. As for technique I just let the electric starter have at it until the gauges stopped.

[tz375]

HF gauges are notorious for reading 60PSI . I'd go and borrow one form Pep boys again and try it on the lawn mower or a different bike or the family car - if you can get to the plugs and see what it reads. I suspect it will read very low.

[Col90]

I did rent one from pepboys today and got the same results as before. I will give the tape a go and if that doesn't work then...

[Coyote]

I have a Sears compression tester. It has an o-ring on the adapter. Can't leak

[Col90]

I think when I get home I will just head to sears and buy a better gauge as I am sick of dealing with cheap 20 dollar ones.

[Coyote]

How did you prep the cylinders? Gaskets new top and bottom?

[tz375]

How many times did you turn the motor over and were the carbs wide open?

[Col90]

New head and base gaskets. I used the electric start and cranked it until the gauge stopped.

[Coyote]

TZ, I think he said earlier that the carbs are off. I think that's the best case scenario isn't it?

Col90, did you lightly hone the cylinders or put them back on as they were?

[Col90]

Both the carbs and exhaust are currently off the bike. I did have the cylinders honed by an experienced motorcycle mechanic/machinist; I also brought him the pistons when I got them in and he said everything looked fine. I just have a feeling these gauges aren't working properly so I'll try the new auto parts store near my house as they probably have a loaner that isn't as used as the other.

[tz375]

Good. Pipes and carbs off eliminates all manner of extraneous issues. Now it's down to gauges or bores.

At 30-60 psi there would be little to no discernible compression. That's effectively 2:1 or 4:1, which is why I suspect the gauges.

[Col90]

I've got some great news. I went out and bought a better compression tester from an auto parts store and these were the results:
left:130 130 130 center: 122 125 125 right: 125 130 130

So it turns out the rented checker and the harbor freight one were messed up from the start. I am so excited that I cant wait until tomorrow and I will start reassembly tonight. Thank you guys so much for your help, I really appreciate you taking the time to help me. On a side note I also need to replace the sris tubing since I had to cut it. How is it mounted on the crankcase, is it the same way as the cylinders?

[yeadon_m]

Great news! the following is from my GT550A and is the same as the Haynes manual. Not the same routing as on GT750, I think.

RH crankcase SRIS goes to LH cylinder

C crankcase SRIS goes to RH cylinder

LH crankcase SRIS goes to C cylinder

Mike

[Coyote]

The SRIS is mounted the same at both ends. 6 'clips' are involved. Both hoses and clips are still available from Suzuki. You will need 3 of part number 09343-02009 (hoses) and 6 of part number 09401-04401 (clips). The clips are nothing more than a thin wall split sleeve and in most cases are reusable. Pry the clips back with a small screwdriver or similar. Pull off the hose and remove the clips. Slip the clips on the new hose and mount all 3 to the crankcase, or you can go one at a time to avoid confusion. I remember when I did mine I had to cut off excess hose on at least 2 hoses after routing them up to the cylinders.
Great news on the reality compression check!