Lowering engagement rpm on LTD...

[shizznats]

Hey guys. We would love to get some advice on how to lower the engagement speed on our LTD motor to about 3000rpm. We rebuilt a spare 1982 LTD motor and are using it for a project which requires lower engagement. I did a lot of reading about clutch tuning in the past few days and have an idea of what dictates engagement speed in a primary clutch. Our 1982 LTD primary has a pink spring and "J" weight ramps with no additional weights added, and it engages at 4400rpm. Our first thought was to put some washers on the weight ramp bolts to decrease the engagement speed but this has the drawback that it will also create much faster shifting once the clutch engages. Also, after adding about 3 grams of weight to each ramp, we didn't notice any lowering of the engagement speed.

Instead, we are now thinking that changing out our ramps may be the best solution. The "J" ramps in our current setup have a prominent engagement notch near the tip of the ramp which is keeping the clutch from engaging easily. Our first thought was to grind these notches down a hair, but after doing some more research, it seems that switching in a different set of ramps into our clutch may do the trick. Can anyone steer us in the right direction as far as which ramps might give us the desired engagement speed of ~3000rpm? For example, the 78 Intruder manual says that with a yellow spring and "E" ramps, the engagement speed is 3600rpm. We are thinking that with the pink spring being the softest, "E" ramps may just bring us close to 3000rpm. Any thoughts on this/advice are greatly appreciated!

[kawhead]

e,c or f ramps is what id try....prefer f.....id set up for 3600 like an intruder, 3000 will be pretty boggy without some steep gear reduction.

[Checkmarks]

Your motor is designed to operate between 6-8k.  At your desired engagement of 3k the motor will stumble and sputter up rpm's.  Have you noticed the idle rpm of these motors are at 3k?  High idle is inherent to two stroke piston port motors.  These little two strokers have no torque or Hp at low rpm.  You can make them idle at 1500rpm but you will wait until 3.5k before you have enough power to move something.

Four strokers on the other hand are much better at low rpm power.  Even reed port motor have an advantage at low rpm.   

If you still need to use the motor design a different clutching system.   

[shizznats]

Thanks for the responses guys. We put E ramps in with a pink spring which brought our engagement speed down to about 3300rpm... but as is mentioned here, there is very low power/torque at that rpm which results in bogging. Going to try some F ramps possibly...

[shizznats]

Quick question.... I noticed from the shop manual on this page that the 1981 LTD had a white spring, F ramps with 1.5g of weight on each ramp, and an engagement speed of 4400rpm. However, I know that for 1982, Kawasaki changed to a pink spring and J ramps with no weights... but I don't know the stock engagement speed for the 1982 LTD because the shop manual isn't available.

Does anyone have a manual lying around or know off the top of their head what the engagement speed is for a 1982 LTD? Also, I'm curious as to the reasoning for the change in spring/ramps from 1981-1982. Thanks!

[kawhead]

j ramps have a pretty aggressive engagement notch and engage around 5 k.  pink spring is made for j ramps, too short, try a yellow with e ramps

[shizznats]

wow, didn't realize the 82 LTD engaged at such a high rpm. Yellow spring with E ramps is what we'll be trying next. Thanks!

[Mister Twister]

Good info here. I'm setting up a 79 invader for drags. Running the LTD twin pipes modified to remove the mufflers with about 18" stingers on them after the cone section. Need to raise engagement and assuming I have stock clutching. Once engaged is pulls hard, so I have secondary set up pretty good. Just not familiar with the kawi primaries. Polaris yes, Kawi no. Looking like the pink and J might work for me. Where can I find them?

[gixxer6]

I never had much luck running the notched J ramps on an Invader...  On my stock Invader 440, I've had great results with modified E's.  I modified them to Aaen spec, then selected spring a weight combo for correct 8,000 redline with a wicked launch.  This was a excellent setup for drag racing, but not very trail friendly...

[Mister Twister]

This thing will never see the trail again. Ovaled it last year, but it just won't run with a twister or an SRX, and there are to many of them to compete with so I'll just stick to running one of my twisters or my SRX in the ovals this year. Where can I find the specs to mod the stuff I have?

[gixxer6]

Its in the members area in the Aaen pipe Instructions.  Keep in mind when you read it, that you'll do more harm than good to try and run anything higher than 8,000 rpm without pipes and porting...

I can't recall exactly what weight/spring combo I ended up with.  But I think it was a red spring.  I still have my "race" clutch assembled on the shelf.  This topic seems to come up quite often...maybe I should take it apart and get the exact specs...