Thread: CT90 question

I have a 1969 CT90K1 that I rescued years ago that was chained to a light pole. I start it a couple of times a year, keep fairly fresh gas in it (with stabilizer in the gas), and drain the carb. I don't remember when I rode it last or what its performance was like when I did. I rode it for about 10 miles or more yesterday. It sputtered a bit when the throttle was wide open, but other than that, seem to run alright on flat ground. Anytime we would go up a hill in the road, it would struggle to get up the hill. I would have to downshift to first or second and my speed went from about 40 to 10 or 15 mph, with the throttle wide open. Even on flat ground, it seemed to be a little underpowered. I do have the high/low gear lever set to high. Sometime years ago, I had the cylinder bored and put in a new piston (maybe because I thought it was sluggish, but I don't remember for sure). I don't know if I ever checked the valves, but I think I did set the timing statically. I assume that I did all that correctly. Any advice on the power issue? Just wondering if these are normally a little sluggish and underpowered?

Have you checked your air cleaner? It may have gotten dirty sitting or maybe a critter crawled in.

Also could be your main piolot circuit. Poor in some Seafoam in the gas and see if that will help clean the carbs insides.

Points not gapped right could also cause this.

How is your compression in the cylinder?

The filter is new, but I just pulled it off to be sure nothing had crawled in. It is clean and nothing plugging up the breather hole. The carb was new years ago and probably only has 100 miles on it. I did pull it and clean the jets before riding it. I'll get some Seafoam anyway and pour it in. Certainly can't hurt the situation. I'll check the points over the weekend and report back. I never checked the compression on the cylinder (or leak checked). Feels pretty tight when kicking it over, but more mushy than a crisp kick. Not sure if that is normal. Do you know? I have a friend that has a C70 and it feels sort of the same soft and mushy when you kickstart his. Based on your suggestions, do you think the power loss up the hills is not normal?