KLX 250 ( 300 ) camshaft mod by Marcelino
#12
06-23-2011, 02:30 PM
Join Date: May 2006
Location: Pittsburgh, PA
Posts: 12,584
@ EMS 0525 :Removig the ACR may be all fine and dandy but there are quite a few peple who have a bone to pick with the idler gear on the kick start . I don´t have one , mine it´s only electric start but if I would , I would have put a needle bearing in the sucker and be done with it .
I´ve had 250´s and 350´s before , one with no decompresor ( compresion ratio = 11 ) , the other ( C.R. 9 ) with a broken manual one and never had a problemm with starting , idlers etc.
I´ve had 250´s and 350´s before , one with no decompresor ( compresion ratio = 11 ) , the other ( C.R. 9 ) with a broken manual one and never had a problemm with starting , idlers etc.
#13
06-23-2011, 02:34 PM
hmmmm..... This really has my curiosity going now... might just have to take my time and do this over winter... Just take off the ACR. This does make sense, when my timing chain was bad it ran like a raped ape, right then i knew that messing with the timing could get alot more HP. Monkeying with this getting ~5 HP is like a 25% increase. If done wrong i can see it going very badly though.
#16
06-23-2011, 03:32 PM
I can't speak for the Europe bikes but as for the AUS and US bikes there seems to be some shortfalls in power in the bikes the USA get vs the Australasian models. This isn't a new thing either. The earliest models gave significantly different outputs on supposedly identical engines. The only differences I can see from the documentation available is in the ignition timing, in particular, the advance.
I'll share the info I have .
All models KLX 250 and 300 from 93 to the latest model share the same cam timing.
Inlet Open 22º BTDC
Close 62º ATDC
Duration 264º
Exhaust Open 61º
Close 19º
Duration 260º
The KLX250 D1,D2,D3,D4 bikes were the most powerful for the engine size (only 1 hp less powerful than the KLX300 A2.)
KLX250 D1-4. (non US model) 32 HP @ 8500rpm (US model) 30.5 HP @ 8500rpm.
Ignition timing: 5º BDTC @ 1700rpm to 40º BTDC @ 3000rpm
Dry Weight 104 KG.
KLX250 E1, E2, E3. bikes were heavier (rack large glass headlight etc.) and pretty much what we get today.
KLX250 E1-3. AUS spec 25 HP @ 8000rpm.
Ignition timing: 5º BTDC @ 1300rpm to 35º BTDC @ 5000 rpm.
(This is the ignition the I have on my 07 KLX250RH7 AUS spec bike, OE. Seems it can be traced back all the way to 94 with the E model bikes.)
KLX250S (09 and on.) AUS spec 23 HP @ 8500rpm (US spec) 15 HP @ 8000rpm.
Ignition timing: (US spec) 10º BTDC @ 1300rpm to 25º BTDC @5000 rpm. (AUS spec) BTDC 10º @ 1300rpm to 35º BTDC @ 5000rpm.
KLX300 A2. (AUS spec) 33 HP @ 8500rpm (US spec) 26 HP @ 7000rpm.
Ignition timing: 10º BTDC @ 1700rpm to 40º BTDC @ 3000rpm
There are differences in power and ignition as I've displayed. Interesting to note that the KLX300 A2 has 40º of advance from only 3000rpm and the KLX250 D series bikes have the same maximum advance from the same rpm. The D series bikes make just 1 hp less than the 300 A2 bike despite having 50cc less.
Makes me think that when I finally fit up the Kawa' 300 kit I have sitting in the garage I could possible be on my way to 30 HP, given the max advance I'm working with (35º) is close to that of the D series 250cc and A2 300cc bikes.
Although 40º advance from 3000rpm sounds like the way to big HP from these bikes. Pity it's not a viable mod as the charging systems are AC vs DC.
I'll share the info I have .
All models KLX 250 and 300 from 93 to the latest model share the same cam timing.
Inlet Open 22º BTDC
Close 62º ATDC
Duration 264º
Exhaust Open 61º
Close 19º
Duration 260º
The KLX250 D1,D2,D3,D4 bikes were the most powerful for the engine size (only 1 hp less powerful than the KLX300 A2.)
KLX250 D1-4. (non US model) 32 HP @ 8500rpm (US model) 30.5 HP @ 8500rpm.
Ignition timing: 5º BDTC @ 1700rpm to 40º BTDC @ 3000rpm
Dry Weight 104 KG.
KLX250 E1, E2, E3. bikes were heavier (rack large glass headlight etc.) and pretty much what we get today.
KLX250 E1-3. AUS spec 25 HP @ 8000rpm.
Ignition timing: 5º BTDC @ 1300rpm to 35º BTDC @ 5000 rpm.
(This is the ignition the I have on my 07 KLX250RH7 AUS spec bike, OE. Seems it can be traced back all the way to 94 with the E model bikes.)
KLX250S (09 and on.) AUS spec 23 HP @ 8500rpm (US spec) 15 HP @ 8000rpm.
Ignition timing: (US spec) 10º BTDC @ 1300rpm to 25º BTDC @5000 rpm. (AUS spec) BTDC 10º @ 1300rpm to 35º BTDC @ 5000rpm.
KLX300 A2. (AUS spec) 33 HP @ 8500rpm (US spec) 26 HP @ 7000rpm.
Ignition timing: 10º BTDC @ 1700rpm to 40º BTDC @ 3000rpm
There are differences in power and ignition as I've displayed. Interesting to note that the KLX300 A2 has 40º of advance from only 3000rpm and the KLX250 D series bikes have the same maximum advance from the same rpm. The D series bikes make just 1 hp less than the 300 A2 bike despite having 50cc less.
Makes me think that when I finally fit up the Kawa' 300 kit I have sitting in the garage I could possible be on my way to 30 HP, given the max advance I'm working with (35º) is close to that of the D series 250cc and A2 300cc bikes.
Although 40º advance from 3000rpm sounds like the way to big HP from these bikes. Pity it's not a viable mod as the charging systems are AC vs DC.
Last edited by WestOzKLX; 06-23-2011 at 04:05 PM.
#17
06-23-2011, 04:08 PM
Yes, I'm doing it tomorrow along with installing Dynojet kit, 351 big bore, crankcase breather mod, uni air filter backfire screen and airbox lid removed. I'm putting it on the Dyno before and after. I'll post results before and after.
#18
06-23-2011, 04:25 PM
Join Date: May 2011
Location: Spain
Posts: 123
WestOZ , the numbers I have for the D1 and D2 are 28 HP , the 300 A 33 HP
Then they changed the generator , changed from CDI to igniter with different spark mapping , and got 21 HP for the 250 and 25 for the 300 . If you are rally iching for the ancient CDI you can take out one of the 3 wires with AC comming into the regulator , pass it trough a 1 to 5 transformer and voila : you have the 60 V ac ( 12 x 5 ) that you need for the CDI .
I think the earliest KLX´s had some 270 degres cams , the other cam timings you have ( 98% of the KLX´s alive ) are spot on , that´s why I said my cam mod is valid for all KLX´s .
Then they changed the generator , changed from CDI to igniter with different spark mapping , and got 21 HP for the 250 and 25 for the 300 . If you are rally iching for the ancient CDI you can take out one of the 3 wires with AC comming into the regulator , pass it trough a 1 to 5 transformer and voila : you have the 60 V ac ( 12 x 5 ) that you need for the CDI .
I think the earliest KLX´s had some 270 degres cams , the other cam timings you have ( 98% of the KLX´s alive ) are spot on , that´s why I said my cam mod is valid for all KLX´s .
#19
06-23-2011, 04:31 PM
Join Date: May 2011
Location: Spain
Posts: 123
Don´t forget that you might need a different jetting if you do the cam mod , if you have rejetted before , know how to tell the difference between poor , right or rich , you should have no problemm . But then again you might not , you can only try and see ...
