Cam timing FXR150

[hmurphy]

Ok so I have done all the measuring and my Intake Valve Opening shows that I am 2.85 degrees out but my lift is sweet. I will find a way to drill holes at maybe 92.85 degrees from the current holes.

My Exhaust Valve Opening is showing 152.025 degrees on the degree wheel but I am unsure what I am supposed to do with this figure. It is supposed to be 41 degrees according to the cam card. Am I supposed to subtract 152.025 from 180 (27.975 degrees)? That's the only thing I can think of that brings it close to 41 degrees but it seems a long way out.

[saxet]

Posted this in the ESE thread but should have gone here, bit of a double up but never mind.
In the mean time if anyone else wants to give this software a go its available free from
http://www.lotuscars.com/engineering...ware-downloads

Attachment 232243

Thanks for the link. I hope to try it out, if I can figure it out.

[saxet]

Ok so I have done all the measuring and my Intake Valve Opening shows that I am 2.85 degrees out but my lift is sweet. I will find a way to drill holes at maybe 92.85 degrees from the current holes.

My Exhaust Valve Opening is showing 152.025 degrees on the degree wheel but I am unsure what I am supposed to do with this figure. It is supposed to be 41 degrees according to the cam card. Am I supposed to subtract 152.025 from 180 (27.975 degrees)? That's the only thing I can think of that brings it close to 41 degrees but it seems a long way out.

Usually the timing specs are Before or After Top Dead Centre or Bottom Dead Centre,
BTDC, ATDC ect, I'm confident you knew that but just to confirm.
Not sure why you want to redrill your intake sprocket so much, would'a thought slotting would do.

If you need holes put in your sprockets try Carl (Karl?) at Cemeck, Fitzherbert st. Petone

TZ's post last page about symmetrical valve timing during the exhaust/intake overlap seems right.

[hmurphy]

Slotting? Does that mean to elongate the existing holes by a small amount?

[Henk]

That would be right.
If you can mark the cam and sprocket at the standard positions before you take it all to bits so you have some sort of known point to revert to if it all gets too messy.

[Ray LeCheminant]

That would be right.
If you can mark the cam and sprocket at the standard positions before you take it all to bits so you have some sort of known point to revert to if it all gets too messy.

Tamiya enamel paint pen does the trick real good!!!

[k14]

Posted this in the ESE thread but should have gone here, bit of a double up but never mind.
Ive been playing with engine performance and evaluation software called lesoft. With all my FXR data entered (64mm piston, 12:1 comp, etc) its suggesting the standard cam timing can be tweeked to give it a bit more go. Have attached the simulators output graph for standard timing, inlet change only and optimised inlet and exhaust timing (the -deg refers to inlet open BTDC and the +deg refers to exhaust closing ATDC, its my own convention designed to confuse everyone but me), Ill update with a dyno run vs the simulators prediction in the near future. In the mean time if anyone else wants to give this software a go its available free from
http://www.lotuscars.com/engineering...ware-downloads

Attachment 232243

Do you know if I used it for my CB125T and just modeled one cylinder would it be effectively the same? Seeing as they are essentially two independent singles on the same crank it should be ok? Unless anyone knows of some simulation software for twins?

[kel]

Do you know if I used it for my CB125T and just modeled one cylinder would it be effectively the same?

If your running independent exhaust then yeah it would be ok for optimising your cam timing, inlet and exhaust lengths. There's good gains to be had in matching lengths correctly. You'll have to do a fair amount of reading and measuring but once you have your model sorted its good fun to watch it optimise. ps it helps to have a really fast computer with plenty of memory, like my work machine

[richban]

Hey Hamish

Since you have Kelford cams and you will have the tech card try running through this if you haven't already. Should all correspond with the info you have on the card.

http://www.kelford.co.nz/sole-purpos...eeing-your-cam

[hmurphy]

Yah I used that page a lot, along with other videos etc.

Also....


I is done!!

[hmurphy]

Hey did you guys need to use a smaller main jet after timing in your new race cams? I had to put the smallest main jet I have in the bike to get it to run close to ok, if I go bigger it gets worse. I was expecting to have to use a bigger main jet. It starts and idles well and takes throttle ok but currently HATES trying to pull from low revs. It used to love pulling from low revs. Obviously tuning issues at the moment that I will get round to. I'm back studying now so don't have heaps of time.

[F5 Dave]

Having never had to fool around with damn silly cam thingys I can't give specifics from experience, but you have changed the timing of the opening & presumably introduced a whole heap more overlap so it makes sense that the jetting will alter.

Try measure the compression, that will have dropped so you have obviously gone backward & you should reinstall the std cams, along with carb & muffler.


(worth a try)

[kel]

you should reinstall the std cams, along with carb & muffler.
(worth a try)

Im with F5 Dave. The bike will be quiet, reliable and fuel efficient, just as Mr Suzuki intended.

[hmurphy]

Ok so I put the std cams back in and I found my stock exhaust and carb and put those on too. I can't believe it... it's sooooo fast now!!!

Ok so anyone remember if they went up or down in main jet sizes with the race cams??

[hmurphy]

I have done a number of changes to the bike that seem to be working ok but I need a smaller main jet. I am using a PKW carb from the Akunar website (http://www.akunar.com/CARBURETTORS.html - the one at the top, 30mm) and I was wondering if anyone has any jets that are smaller than a 118 for this? It is very, very close to being right at the moment, but definitely needs to be leaner. I have tried bigger main jets and full throttle gets worse (it can't clear out at high RPM with full throttle) so definitely need to go a bit leaner than 118.
The spark plug looked fine after doing a plug chop, and it feels close but it misses a little up top.

On the bright side, the power is far more aggressive and it pulls pretty hard from reasonably low but WOW it pulls much, much better from mid to top.

Cheers