My new to me 780 srx is junk!!!!

blueblooded

blueblooded

Member
Joined
May 16, 2003
Messages
856
Age
53
Location
Lockport ny
I just bought a 2000 srx 700 with a 780 big bore off a fellow TY member and on my first trip out the motor is toast.I took it to full power performance and found out the center piston skirt and cylinder broke.I have two options.Rebuild the 780 which needs new pistons,center cylinder and center reed cage.The second option and recommended way to go is sell the big bore kit and use ported stock cylinders which should give me better reliabilty and 160-162 h.p. but this will cost me 2700.00!!!!!!! What should i do i just want a fast RELIABLE trail sled.
 

i would personally try to sell it ought right or part the sled out.you could make quite a bit of money!! you can pick up a viper for pretty reasonable. i saw one on ty for 2600 and im sure you could talk him down.
 
I was told the center cylinder is repairable and the other two are fine.The heads are all good also.It had wiesco pistons in it which two are ok one needs to be replaced.Hauck sells the pistons i was told.I also have the power valves that go with it.
 
I dont think the 780 required aftermarket pipes. It sounds like the wisecos costed you alot in damage.

3 new pistons, rings, and a cylinder repair nets you around $600. I would reapir it and be done with it.
 
mm700sleder said:
what would that include. could you give me the details, and i assume this would fit a viper
Click to expand...


3 good heads
2 good cylinders
1 cylinder needing repair
3 power valves
2 good pistons
need one piston
Im not selling the stock pipes as i will need them.
 
You are not going to end up with 160-162hp on a trail ported 700. 150-152hp would be more accurate. The big bore would be in the 160 hp range.

The parts that they have described to you would certainly not be in the 2700 range. To have a cylinder re-nicasiled (sp?) only costs me $290, and i'm up in Canada. All 3 pistons/rings/pins would probably run $450 max. I'm sure you could find a used factory reed cage for $30. Sure, labour would come into account, but would be nowhere near that quote. I would find someone else to rebuild your motor, and it should cost you less than $1K, all in.
 
I think mrviper has his ways of getting good pistons for this motor.

$600 in repairs and be done with it. or see if you can buy a COMPLETE stock top end, whichever price is better because I think a complete ported stock top-end will be hard to find. But remember, porting a stock top end will be more money cause I know thats what you want.
 
Stock SRX pipes work great with this kit. I imagine you can run bigger pipes though if you wanted.
 
if i can get into this big bore kit for reasonable and he can find stock parts, im a buyer. i just need to find someone with some pipes
 
I was told the 780 is weak because the material is so thin at the bottom of the cylinder and they tend to break,also you have to run a lot of piston clearance with the wiesco pistons which tend to beat up the motor over time.He told me using a stock bore cylinder with the porting is much more reliable.I want to stick with the big bore because its cheaper to fix but i dont want reliabilty problems down the road.
 
Sell the BB crap, buy stock, rebuild it taking your time and using OEM Yamaha parts and enjoy a fast/reliable a$$ stock sled.
 
humm i have a freshly ported mr viper 01 top end, 600 miles on it, i might consider going to 780, it pull like crazy witht the ported motor , don's work is second to none, but i still want more power lol, got to pass my buddys attacks lol. I might consider trading plus $$ on you part, ill let you know, pm me if your interested. Im going to talk to don about the 780, well see what he tells me, i always listen to him, up to know hes always right!
 
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