Max. RPMs

elkhunter338 · 04-24-2019, 11:53 PM

two questions to chime in on, I want engine longevity kept in mind. Motor that will likely run 20,000 miles +

At what rpm's would you consider max. for sustained time periods?

My thought based on no real data other than what CSC has posted on their posts regarding running the bikes on adventure trips. They have said many times they have run their bikes a few 100 rpm's below max.
tt250 max. hp is at 7,000 rpms. They run them at 6,800 for hours on end?

For short bursts, I am guessing 7-8,000 rpms is ok?

Megadan · 04-25-2019, 01:11 AM

Quote:

Originally Posted by elkhunter338

two questions to chime in on, I want engine longevity kept in mind. Motor that will likely run 20,000 miles +

At what rpm's would you consider max. for sustained time periods?

My thought based on no real data other than what CSC has posted on their posts regarding running the bikes on adventure trips. They have said many times they have run their bikes a few 100 rpm's below max.
tt250 max. hp is at 7,000 rpms. They run them at 6,800 for hours on end?

For short bursts, I am guessing 7-8,000 rpms is ok?

With such a small bore and stroke these little engines can get away with running at higher revs than what you would think. That said, for sustained periods I did tend to like keeping mine at or below about 7000rpm. The engines tend to be happiest at crusing speed between 6000 and 7000 in most cases.

The crucial thing is that your fueling is dialed in, because you will start tapping into the main jet when trying to sustain highway speeds. Being lean with the throttle cranked at high rpm for long periods of time can be unfriendly to engines.

Tashka · 04-25-2019, 02:07 AM

Before I tuned my hawk, it was running pretty lean where I'm at. It would run fine, but it would get HOTTTT if ran at max for like 20 minutes or so(stock sprockets too).

However after I put the new exhaust and new carb and tuned it, It'd run max for a long time before I would worry, Definitely lots of vibrations at that rpm though. I drove like 38 miles on the highway to visit a friend when it was my only vehicle.

It kept it maxed the whole way there, once I got off my legs and arms were like jelly. Took some rest to drive it back lol.

I wouldnt see any reason it shouldn't be fine. If you do lots of highway, it might be smart to get an oil cooler and just gear it high for so you're not redlining at top speed.

The bike reallly loves 6-7k and honestly i think would run rabid like that all day

**JerryHawk250** · 04-25-2019, 07:57 AM

Like Dan said, these engine are in there happy place between the 6000-7000 rpm range. I change the front sprocket depending on what type of riding I'm doing. With a 17 tooth on from I can cruise 60-70 mph and not have the throttle pegged. An oil cooler would be a good idea if you plan on making long trips at high speeds.

upgasgas1224 · 04-25-2019, 08:27 AM

mabye im crazy but after 3000 miles on the engine with no hick ups i frequent 8k rpms for extended duration's kinda have it in my head that any rpms under 9k the bike handles just fine so far. i wonder how long its gonna hold up tho so basically im trying to blow it up and it hasnt yet and shows no sign of slowing down. i never broke 7k rpms tho for the first 1000 miles. i have been playing with the idea of going to a different rear sprocket again mabye a 42 or somthing just so at max speed its closer to the 7k mark but im worried ill loose the offroad grunt

**JerryHawk250** · 04-25-2019, 08:42 AM

Quote:

Originally Posted by upgasgas1224

mabye im crazy but after 3000 miles on the engine with no hick ups i frequent 8k rpms for extended duration's kinda have it in my head that any rpms under 9k the bike handles just fine so far. i wonder how long its gonna hold up tho so basically im trying to blow it up and it hasnt yet and shows no sign of slowing down. i never broke 7k rpms tho for the first 1000 miles. i have been playing with the idea of going to a different rear sprocket again mabye a 42 or somthing just so at max speed its closer to the 7k mark but im worried ill loose the offroad grunt

I just swap my front sprocket to a 15 tooth when I go off road.

Megadan · 04-25-2019, 11:48 AM

Quote:

Originally Posted by upgasgas1224

i have been playing with the idea of going to a different rear sprocket again mabye a 42 or somthing just so at max speed its closer to the 7k mark but im worried ill loose the offroad grunt

That is the reason the 17/45 is such a popular combination. It is the happiest middle ground between overall street/highway capability and off road usability.

I really enjoyed my 43 rear sprocket, but it does give up a bit of grunt for off road riding, and it does require lots of clutch use in slow speed crawling. As Jerry mentioned, I got into the habit of swapping over to a 15 tooth front if I planned on using it more strictly off road. It takes 10 minutes to swap, and you can even toss the extra sprocket in a bag, pocket, or burrito tube.

elkhunter338 · 04-25-2019, 11:27 PM

I am basically geared for off road use, but will sometimes hit a paved road in a rural area where I can putter along at 35mph or so and let cars go faster if they catch up. Traffic volume will be very minimal. Hit a paved road run 2-3 miles then take to the off road adventure.
With my gearing 14/56 I am going to be running about 6,500 @ 35 mph and was wondering just how much I could push it in the rpm's to get 40 maybe 45 for topend speed. Geared like this I won't be full throttle, just running high rpms under essentially only a moderate load.

Sounds like running 7,000 is no issue.

04-24-2019, 11:53 PM	#1
elkhunter338 Join Date: Dec 2018 Location: Oregon Posts: 81	Max. RPMs two questions to chime in on, I want engine longevity kept in mind. Motor that will likely run 20,000 miles + At what rpm's would you consider max. for sustained time periods? My thought based on no real data other than what CSC has posted on their posts regarding running the bikes on adventure trips. They have said many times they have run their bikes a few 100 rpm's below max. tt250 max. hp is at 7,000 rpms. They run them at 6,800 for hours on end? For short bursts, I am guessing 7-8,000 rpms is ok?
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04-25-2019, 07:57 AM	#4
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,585	Like Dan said, these engine are in there happy place between the 6000-7000 rpm range. I change the front sprocket depending on what type of riding I'm doing. With a 17 tooth on from I can cruise 60-70 mph and not have the throttle pegged. An oil cooler would be a good idea if you plan on making long trips at high speeds. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S (Sold) 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
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04-25-2019, 08:27 AM	#5
upgasgas1224 Join Date: May 2017 Location: Michigan Posts: 107	mabye im crazy but after 3000 miles on the engine with no hick ups i frequent 8k rpms for extended duration's kinda have it in my head that any rpms under 9k the bike handles just fine so far. i wonder how long its gonna hold up tho so basically im trying to blow it up and it hasnt yet and shows no sign of slowing down. i never broke 7k rpms tho for the first 1000 miles. i have been playing with the idea of going to a different rear sprocket again mabye a 42 or somthing just so at max speed its closer to the 7k mark but im worried ill loose the offroad grunt __________________ 04 flywing 150 05 flywing 150 07 gasgas ec200 18 csc tt250 / foam filter mod, amazon exhaust, mikunki carb, 47tooth sprocket, o ring chain, stereo system, amsoil oil, honda 10w fork oil, tusk bars and brush guards.... more to come
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04-25-2019, 02:07 AM	#3
Tashka Join Date: Aug 2018 Posts: 158	Before I tuned my hawk, it was running pretty lean where I'm at. It would run fine, but it would get HOTTTT if ran at max for like 20 minutes or so(stock sprockets too). However after I put the new exhaust and new carb and tuned it, It'd run max for a long time before I would worry, Definitely lots of vibrations at that rpm though. I drove like 38 miles on the highway to visit a friend when it was my only vehicle. It kept it maxed the whole way there, once I got off my legs and arms were like jelly. Took some rest to drive it back lol. I wouldnt see any reason it shouldn't be fine. If you do lots of highway, it might be smart to get an oil cooler and just gear it high for so you're not redlining at top speed. The bike reallly loves 6-7k and honestly i think would run rabid like that all day
	0

04-25-2019, 11:27 PM	#8
elkhunter338 Join Date: Dec 2018 Location: Oregon Posts: 81	I am basically geared for off road use, but will sometimes hit a paved road in a rural area where I can putter along at 35mph or so and let cars go faster if they catch up. Traffic volume will be very minimal. Hit a paved road run 2-3 miles then take to the off road adventure. With my gearing 14/56 I am going to be running about 6,500 @ 35 mph and was wondering just how much I could push it in the rpm's to get 40 maybe 45 for topend speed. Geared like this I won't be full throttle, just running high rpms under essentially only a moderate load. Sounds like running 7,000 is no issue.
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