Loss of power Suzuki DT65 1993

[suzuki104]

Can anyone help? My DT65 has lost full power. I Initially thought a fuel blockage so clean carbs but they were clean. Then I checked the fuel diagphram which had perished. This was replaced. The start up was fine and seemed to tick over better ie all 3 cylinders. I took it out for an open water test and I still can only manage 13knots on an alaska 500. Before I was managing 26 to 28knts full throttle. Fuel consumption has over doubled. Impellor has been replaced yet still has temperamental output. There is no wax thermostat in the housing so should pump consistently.

What should I check next.? There is spark on all three plugs. It feels like fuel starvation.
Thanks Allan

 

[mphelle8vld]

Re: Loss of power Suzuki DT65 1993

Start with the basics and perform a compression check.

Motor could have overheated and scuffed the pistons or with a torn fuel pump diaphram, raw fuel could be sucked into cylinder #3 washing oil off of the cylinder wall and toasting that piston.

 

[suzuki104]

Re: Loss of power Suzuki DT65 1993

Thanks for that . However been doing some more tests and have noticed that No1 sparkplug was greyish white. 2 and 3 normal. Now the intresting part. When I initially start engine it ticks over fine. When water is drawn up the leg and water comes out of exhaust port under the cowling and water flows out of pilot jet it starts coughing , and spluttering and eventually dies on tick over. This does it everytime. Head gasket? and if so having done cars and bike head gaskets is it easy to replace.

 

[99yam40]

Re: Loss of power Suzuki DT65 1993

Sounds like a carb problems not head gasket

 

[mphelle8vld]

Re: Loss of power Suzuki DT65 1993

You can get a lot of information in 5 minutes with a compression check, including the integrity of the head gasket. If your numbers are all around 120psi, I'll be getting on 99yam40's bandwagon.

 

[suzuki104]

Re: Loss of power Suzuki DT65 1993

Now found the problem. No1 piston no compression whatsoever. 2 and 3 plus 120psi each. Stirpped it all down and engine now out and splitting block. No1 piston had a hole in it. So far no other damage. Bores and crank seem fine. questions

1. What caused the hole in the piston, was it the fuel pump membrane perishing allowing neat fuel into the pot and burning at a higher temp?

2. Can I get away with replacing the damaged piston and rings and leaving the other 2.

Hope this has all been worth it so far. Engine has come apart quite well for its age. Any other tips on the rebuild would be appreciated

 

[suzuki104]

Re: Loss of power Suzuki DT65 1993

Have rebuilt the engine and as it hadnt seized there was no real stress on the crank. Having started it all up it runs ticks over fine. However the flywheel spindle crank shaft end is ocsiclating. Off centre by about 2 mm. I would be surprised if the crankshaft was bent. I did have difficuly in applying the lower crank casing that houses the reeds. I had located all the lugs of the bearings in the keyways at the joing on the crank case and seem to torque down all ok. Is there any obvious divots for seatint the bearing at the flywheel end of the crank as this was where i was having problems. I have now got to strip it all down again. If the worst is a bent crank is it possible to get it repaired or should i CALL IT A DAY.

 

[captain seaweed 10]

Re: Loss of power Suzuki DT65 1993

i just had the same problem, and i replaced the gasket on the outside of the pump , it was sucking air , and then added aviaton fuel , it cleaned it all out , just something for you to try good luck