Tempted to go for more... 1988 Johnson GT100

[Chinewalker]

I have a recently rebuilt 1984 Johnson 90 hp that I have previously posted about. The motor runs great and has run through about 7 tanks of fuel without a problem.

Which brings me to my question - I may have found another motor! I came across a 1988 Johnson GT-100, blown, with one cylinder in need of reboring. The 90hp I am running was rated at the powerhead, while the 100hp is propshaft rated, so I am guessing that on an even playing field the 100hp is akin to a 1984 115. That said, anyone think I would notice a big difference if I went through and rebuilt the GT100 and put it on the boat in place of he 90? The 90 runs well and performs nicely. Peaks out around 5800-5900 RPM and seems really happy. I e-mailed Dhadley on this, but he seems to be out of town for a bit.

Anyone know if the GT100 had the high performance reeds, etc. like the GT150s did?

THanks,
- Scott

 

[emdsapmgr]

Re: Tempted to go for more... 1988 Johnson GT100

A quick look at the high speed jets in the 100 (57c), and they are just one size larger than the 88/90 (56c). The 110 (67c)has the much larger jets. If you are going to make more hp, you need more fuel, and it does not look like the 100 is much different than the 90. Probably not worth putting the money into. If it was the 110, might be another thing. An easy bolt-on addition would be to put a set of 110/115 carbs on your 90-will be worth the expense.