my dyno disappointment

[jas250r]

so i went and dyno'd my ct 350pv at rb place. first runs were at 38hp and 26torq. starting at a 180 main jet. final was 48hp and 30torq with a 165 main. a little background info. ct 350pv first bore, wossner piston, stock stroke, cr ignition with 13oz weight, v-force 2, esr 5 pipe and silencer, esr 40.5 carb. i had rb touch up bone stock port work from ct just a little bit just to allow me have a little bit more on top utilizing the 5 pipe. rb said with esr air box elminator i was planning on using a the dunes the next weekend, i might gain another hp or 2. i left disappointed, wanted to see 50. but after riding all weekend at dunes, i was happy as hell. i know it was far from the fastest thing there. but power was smooooth and pulled really long and hard. just a great all around power. perfect for trails and dunes. hats off to rob. even though i was scared on running such a small jet, but it was exactly what i asked for from him, when i had him touch it up. so i guess numbers aren't all that?

[morse250r]

with a simular build to yours non pv i pulled 55hp with roberts dune porting so id say your close did you advance the cr ign thats where i saw a huge gain on mine

my 363 right now with a 40.5 i have a 162 main in there !!


i wouldnt be disapointed, that a strong runner you have there !!

[C-LEIGH RACING]

Reads to me like the ol butt dynos working better than the wheel dyno.
If it feels good to you riding it, dont let those numbers get you down.
How much did that dyno day cost.
Neil

[8686]

Bob (RB Racing) is an awesome guy. He really knows his stuff and he pays attention to what you as a rider want to get out of the engine. He's done a few engines for me and I have plans for a couple more to head his way. I've always said dyno's are humbling, and they are! Hardly anyone is making the hp they think they are. And 48 hp with only a cleanup port is nothing to be disappointed about. That's some good power. The most important thing is that he helped you optimize your current setup and you guys got your quad running good.

Oh and when you think about it on a percentage basis (which I always do), Bob helped you gain 25% more horsepower and 15% more torque. That's awesome!

[Ruf Racing]

I wouldn't be too concerned with dyno numbers. Dyno's fluctuate to much to give you a accurate reading. They are only good for tuning. Your asss is the best dyno! :macho

[morse250r]

rb 's real fair on dyno prices

my best on his dyno so far is 70hp on gas ill be heading out there soon to switch to alky

[atvmxr]

has anyone seen a 250 make 50+hp? I thought it was pretty common to get a national level 250 around the numbers you have

but I suppose the 350+pv has gobs more torque?

[8686]

Originally posted by atvmxr
has anyone seen a 250 make 50+hp? I thought it was pretty common to get a national level 250 around the numbers you have

but I suppose the 350+pv has gobs more torque?

A 250 making 50+ hp is going to be quite strung out, and I bet it wouldn't last very long on an mx track.

Heck, IMO, a 250 making 40 hp is pretty healthy for sure.

[jas250r]

yeah the dynoing cost me only 50. yeah the butt dyno says it runs great. rob did mention advancing the timing on the cr. i will save that for the next dune trip, for the arch enemy friends with 4pokes. also going to change the gearing from 13-36 to 13-39. i ran a friends 22-12-8 6pdl brats with 4.5 psi. never tried playing with air because i was real consistent on my launching. thanks guys. morse do u recall how much you picked up with advancing the cr ignition

[C-LEIGH RACING]

jas,
If you using the ESR, CR250R to TRX250R ignition adapter plate, dont just advance the timming guessing yourself, tell Rob to use a timming light & TDC dial indicator to set it with.
If you just advance it, good chance you'll have it way over advanced, because of how that ESR adapter plate has been machined.

I learned the hard way just guessing at it & blew a spark plug out from deto.
Later I found my guessing error by using the timming light & indicator set up. My guessing ended up around 25 to 35* advance, ol R ran good, but a price was paid.
Neil

[derby]

Originally posted by C-LEIGH RACING
jas,
If you using the ESR, CR250R to TRX250R ignition adapter plate, dont just advance the timming guessing yourself, tell Rob to use a timming light & TDC dial indicator to set it with.
If you just advance it, good chance you'll have it way over advanced, because of how that ESR adapter plate has been machined.

I learned the hard way just guessing at it & blew a spark plug out from deto.
Later I found my guessing error by using the timming light & indicator set up. My guessing ended up around 25 to 35* advance, ol R ran good, but a price was paid.
Neil

As neil said get a dial indicator if you plan to play with ignitions. And buy a quality one. It is about the same price as a couple of pistons you take your pick.

[morse250r]

i took the stoper plate out and fully advanced it, picked up 7 hp by doing that id suggest going down to a cooler plug br9es
if your not there already, gearing id say jump to a 14 your not tapping into the torq of that motor youll gain alot right there and id be tring a set of 8 paddle extreames those paddle brats arent enough tire for you but the size is good 22" tire with a good roll out.

by advancing my timing ive done it on a few motors no problems never used a light they are machined like that for a reason i was told with that blocker plate in there with a screw so that it could be removed

[C-LEIGH RACING]

Originally posted by morse250r
i took the stoper plate out and fully advanced it, picked up 7 hp by doing that id suggest going down to a cooler plug br9es
if your not there already, gearing id say jump to a 14 your not tapping into the torq of that motor youll gain alot right there and id be tring a set of 8 paddle extreames those paddle brats arent enough tire for you but the size is good 22" tire with a good roll out.

by advancing my timing ive done it on a few motors no problems never used a light they are machined like that for a reason i was told with that blocker plate in there with a screw so that it could be removed


After you removed the little metal plate at the bottom of the CR stator plate, which way did you rotate the stator, clock wise or counter clock wise.
Do you have the ESR, CR ignition adapter plate or the one CT Racing offers.
Neil

[machwon]

Originally posted by morse250r
i took the stoper plate out and fully advanced it, picked up 7 hp by doing that id suggest going down to a cooler plug br9es
if your not there already, gearing id say jump to a 14 your not tapping into the torq of that motor youll gain alot right there and id be tring a set of 8 paddle extreames those paddle brats arent enough tire for you but the size is good 22" tire with a good roll out.

by advancing my timing ive done it on a few motors no problems never used a light they are machined like that for a reason i was told with that blocker plate in there with a screw so that it could be removed

Damn, sounds like another R tuning secret is out. I'm sure you guys already new that one. Dyno's are great at finding that last 10% of the available power. I usually only use my dial indicator on the pvl's. You could also try a dyna programable cdi and compare the timing advances with a stock ignition. The CR curves are way different. What performs better, a CR ignition with no advance or the stock 250R ignition?

[morse250r]

clockwise turned to the right

and its the whole cr set up from esr

[jas250r]

i have another set of paddles that are 21-11-8 8 paddle haulers. i'am running a stock swinger length. so i will give the 14 a shot, keepin the 36 in back. and the advancing too. hey rob could you post the dyno chart for me if you can.

[machwon]

Give me a day or two and I'll get them up.

[jas250r]

thanks rob

Can you explain how you use the dial indicator at TDC...?

Thanks,

C.

[mcboomport]

Bummer! my 250 with stock head/ 4 mill stroker (268.8cc)/ 212 psi/ stock ignition/lightened flywheel/ 38 airstriker/ trx 5 centermount made 48 at the rear tires with a slipping clutch. I've only had this season on it, so we'll see how reliable it is, but man people overlook the potential in the smaller cc'd motors.

[C-LEIGH RACING]

Originally posted by acecarlos
Can you explain how you use the dial indicator at TDC...?

Thanks,

C.

Theres a type of indicator offered that screws into the spark plug hole & once it is screwed in & locked down, when you rotate the crank, the dial needle will tell when the piston stops at TDC.
When you find that point, you'll need to mark a place on the case to match up with the TDC mark on the flywheel. A scratch or soap stone mark will do, just some sort of mark so you'll know when the pistons at TDC.
Soap stone will show up better when using a timming light.

Now once you have that, you'll know for sure when the piston is at TDC by the mark on the case & flywheel. Once you have that done, remove the indicator, put the plug back in & time to start the engine to check ignition timming.
When you use a timming light, when it blinks as the engine is running, it will show by the misalinement of the two marks where the ignition timming is set at.

If the timming is advanced, the mark on the flywheel will be at one spot & then the mark on the case will be at another.
The mark on the case cant move, so what your seeing is the mark on the flywheel being in a different spot that is moving.
If the mark on the flywheel is to the right of the mark on the case, then your ignition setting is advanced, which normaly it will be some, but how much of a gap between the two marks, that will be how much advance the ignition is.

A gap of say 1/4", between the mark on the case & the mark on the flywheel, your probably looking at around 15 to 20* advance, but realy thats just a guess & only real way to know would be if a degree wheel was bolted up on the crank & measured it.
There are some builders, that have done timming setting enough that they can look at the amount of gap with a timming light & know right off how much timming advance the ignition is set at.
Things like that take quite a few years to learn or get the feel of from hands on.
Neil

[86 Quad R]

Originally posted by mcboomport
Bummer! my 250 with stock head/ 4 mill stroker (268.8cc)/ 212 psi/ stock ignition/lightened flywheel/ 38 airstriker/ trx 5 centermount made 48 at the rear tires with a slipping clutch. I've only had this season on it, so we'll see how reliable it is, but man people overlook the potential in the smaller cc'd motors.

yessir! they sure do. :cool:

Neil, as always you are very helpfull; great explanation!

Thanks!

[machwon]

Here is the 1st and last dyno run.