I have a YZF 600R Thundercat that has an intermittent problem. Occasionally, and under load, when it gets to 5500 rpm it feels as if it has a spark missing. This goes on till 6500 rpm when it clears. I have bought a new coil and swapped them around. I have bought new plugs. I have had the carbs off, cleaned them out and also replaced the fuel filter. Could it be the plug caps and if so where can I get some as they seem to be rarer than chickens’ teeth? The only other things I can think of are the throttle sensor and the management system, but naturally these are going to be expensive to buy just to eliminate them. Could this be a bigger problem than I think?

Help!

I have a YZF 600R Thundercat that has an intermittent problem. Occasionally, and under load, when it gets to 5500 rpm it feels as if it has a spark missing. This goes on till 6500 rpm when it clears. I have bought a new coil and swapped them around. I have bought new plugs. I have had the carbs off, cleaned them out and also replaced the fuel filter. Could it be the plug caps and if so where can I get some as they seem to be rarer than chickens’ teeth? The only other things I can think of are the throttle sensor and the management system, but naturally these are going to be expensive to buy just to eliminate them. Could this be a bigger problem than I think?

Help!

Could be the leads or could be the Pick up coil, TPS ...

Best advice is to drop it in to a dealer so they can identify the fault, even if you take it home to repair.

there some leads on ebay going for sale with coils at moment!

http://cgi.ebay.co.uk/YAMAHA-THUNDERCAT-YZ...Q2em118Q2el1247

quite a few on there (search Thundercat coil or Thundercat leads)

or plug caps only

http://cgi.ebay.co.uk/Yamaha-YZF-600-Thund...Q2em118Q2el1247

Thanks Chris.

My 2 nearest dealers are 90 and 120 miles away so I wanted to try as much as I could myself. The leads are integral parts of the coils and I think I have discounted them. Thanks for the links and the advice anyway. The bike is still rideable it’s just that dead spot...

Cheers!

you can buy ngk plug caps from places like deemon tweeks , they are direct replacement parts, try them and see how you go..

you can buy ngk plug caps from places like deemon tweeks , they are direct replacement parts, try them and see how you go..

exactly as jimmy says, the coils come with the leads but do not include the actual plaug caps, I think of the links I provided was just for plug caps.

however, the pick up coil is a totally separate unit (not the same as your ignition coils) so could be that. In all likelyness I'd go for it being the TPS though.

I was out on it again yesterday. It generally runs ok apart from the dead spot or if I open the throttle at low speeds. Above 7000 rpm it’s as sweet as a nut and goes on revving, so this is making me think that it may not be electrical.

I have checked the resistance on the TPS and although it is within tolerance, it is only just.

I am currently trying to get it booked in for a diagnostic so that I don't blow a load of cash on electrical parts that won't cure it.

Cheers for all your help anyway! I'll let you know how I get on.