big bore kit ?//??/

T

torelloracing

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i have a 01 srx and do alot of riding but want more power ... has anyone done or have any imput on any of the big bore kits ? how dependable and how much more power ? thanks
 
I have had 3 BB SRX's 2 - 835's 1 - 780 All I will say is if your going BB find the pipes to work with the kit!! Completely set up a BB SRX is very fast.. You won't be disapointed..
 
jabber800 said:
I have had 3 BB SRX's 2 - 835's 1 - 780 All I will say is if your going BB find the pipes to work with the kit!! Completely set up a BB SRX is very fast.. You won't be disapointed..
Click to expand...

thanks for the 411 is it something i can put some big miles on and not spend the night in the woods!
 
I've been running a 780 motor with the stock pipes for a few years now. Jet it, warm it up properly, and run good fuel and it is as reliable as a stock one. Ride it in the flats of MN and in the mts of WY and MT. Never disappoints.
 
Torelloracing, Have you any engine mods now at all? I only ask because 700 srx trail ports provide a large power increase and are a little more forgiving then a big bore is, and they will give better service life due to thicker rings and pistons that dont expand at a quicker rate.
Your looking at around 10hp differance between a 700 ported and a 780 ported for trail riding. Theres also about roughly $1500-1600 dollars differance in pricing of each.

780 is a great very strong running engine,and as RyanB mentioned,as long as you warm it up very well EVERYTIME you ride it and keep good gas in them, you have no problems. The problems arise from the cylinder is much thinner after being bored and replated for the 780 piston, the piston is a wiseco forged unit, it will expand quickly if not warmed up and is actually harder then the cast cylinder is. This will quickly cold seize a piston and if you have detonation going on from poor fuel, you run the risk of shaking/rocking the piston and breaking off the cylinder skirts. 700 trail ports are the same as stock for reliability, not many cold seizure problems and very long ring life.
Not trying to scare you off just give you good and bad points up front. For higher mileage riders,most times a 700 trail port is sometimes more economical and better suited. For riders who demand ultimate power output and are self controlled on warm ups a 780 is definitely the way to go.

typical trail port 700,mid 150 hp range, $500-600 investment

typical 780 trail port topend, mid 160hp range, $2200-2500 investement

(even more power wanted- aftermarket pipes for the big bore will yield another 10 hp, typical cost-$1100 more)

as you can see it will get into a sizeable investment pretty quickly.
 
torelloracing said:
i have a 01 srx and do alot of riding but want more power ... has anyone done or have any imput on any of the big bore kits ? how dependable and how much more power ? thanks
Click to expand...

I have had a Hauck BB kit in mine for a few years. It has been a big performance improvement and has run like a stock sled as far as having no issues. His kit will give you 165 HP without doing bigger carbs or carb boring.
I Think Aaen and Simmons offer a similar BB kit but I can't speak for theirs.
 
There's no replacement for displacement! But I'd be more interested in porting. I haven't heard a lot of good things about wiseco in yamaha but it looks like some of you have had good luck with them.

How much power we can get often depends on the money we spend!
 
Listen to MrViper, he's built enough engines and knows his s**t, I would send your engine to him and he will hook you up with some power, good luck.
 
nothing wrong with wisecos. i've run em in many apps. including my 780. always operator error if any probs. wisecos are top notch pistons, but as the others stated, you must warm em up properly
 
I have been running bender 835 for 5 years now and its very reliable. I changed pistons at 4000 miles and now have a total af 6800 miles on my motor, runs strong, I have the big bore pipes and the motor was case ported, makes hp in the upper 170"s with stock carbs. I dont run as rich as bender suggested, the key to makeing this motor live is a big heat exchanger, I use a fab craft u exchanger, no thermostat, put a restrictor in the line before coolant goes back into motor with a 3/8 hole in it, good fuel and always always always warm engine up before running. I have a digatron and exhaust temps are right on the money, I have a digital H2O gauge and generally run around 118 degrees temp just before coolant goes back into engine. bender does not use wiseco, they use a cast piston, every wiseco i ever used in any 2 stroke motor blew up, i would not use a wiseco if they were for free. this motor is easy to clutch, i use heel clicker in primary and a heel x roller secendary, gearing 24-35
 
staggs65 said:
nothing wrong with wisecos. i've run em in many apps. including my 780. always operator error if any probs. wisecos are top notch pistons, but as the others stated, you must warm em up properly
Click to expand...


X2 - Some quality issues years ago (name one OEM or AM mfg. that hasn't) but I've had excellent results... with proper warm up.
 
Big Bore

I have been running a Mega Power 780 since 02 in my 01 SRX. I have well over 4000 miles on it. I have the Mega Power heads with trail domes, Bender Big Bore Pipes, and Bored stock carbs. This is my trail sled. I have never ever had a heat issue. This sled runs flawless. I never even fouled a plug. To me the best part of running a Big Bore is the torque. But then again a Big bore is not cheap. The pipes alone cost $1100 new. But as the old saying goes there is no replacement for displacement.
 
If ya check out ebay it's all on there right now. 800 BBkit, carbs the whole shootin match, cheap, I think it was at $300 last night
 
i have one of bender's first 835 big bores. thousands of hard trail miles & no problems. made 194 h.p. @ dynotech w/ winter jetting & 200+ h.p. leaned down, all on pump gas. honvfr is correct on cooling. i plumbed in tunnel heat exchangers. not a cheap pkg.....but lots of smiles per mile.
bob
 
bufalobob said:
i have one of bender's first 835 big bores. thousands of hard trail miles & no problems. made 194 h.p. @ dynotech w/ winter jetting & 200+ h.p. leaned down, all on pump gas. honvfr is correct on cooling. i plumbed in tunnel heat exchangers. not a cheap pkg.....but lots of smiles per mile.bob
Click to expand...

i like that statement bob ;)!
 
What's the downside of the porting? Sure there has to be one or more?
I guess it still won't be as forgiving as stock to bad fuel or jetting a little on the lean side? Is the power moved from one part of the powerband to another?
Can you still hold it to the bar for a mile like you can with the stock set up, with the correct jetting of course?



mrviper700 said:
Torelloracing, Have you any engine mods now at all? I only ask because 700 srx trail ports provide a large power increase and are a little more forgiving then a big bore is, and they will give better service life due to thicker rings and pistons that dont expand at a quicker rate.
Your looking at around 10hp differance between a 700 ported and a 780 ported for trail riding. Theres also about roughly $1500-1600 dollars differance in pricing of each.

780 is a great very strong running engine,and as RyanB mentioned,as long as you warm it up very well EVERYTIME you ride it and keep good gas in them, you have no problems. The problems arise from the cylinder is much thinner after being bored and replated for the 780 piston, the piston is a wiseco forged unit, it will expand quickly if not warmed up and is actually harder then the cast cylinder is. This will quickly cold seize a piston and if you have detonation going on from poor fuel, you run the risk of shaking/rocking the piston and breaking off the cylinder skirts. 700 trail ports are the same as stock for reliability, not many cold seizure problems and very long ring life.
Not trying to scare you off just give you good and bad points up front. For higher mileage riders,most times a 700 trail port is sometimes more economical and better suited. For riders who demand ultimate power output and are self controlled on warm ups a 780 is definitely the way to go.

typical trail port 700,mid 150 hp range, $500-600 investment

typical 780 trail port topend, mid 160hp range, $2200-2500 investement

(even more power wanted- aftermarket pipes for the big bore will yield another 10 hp, typical cost-$1100 more)

as you can see it will get into a sizeable investment pretty quickly.
Click to expand...
 
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