Author Topic: improving bottom end power  (Read 1437 times)

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Offline twinrock

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improving bottom end power
« on: March 31, 2018, 09:59:42 PM »
Hey  looking for some guidance in improving bottom end power and response.
The bike is a dt200r but with a twist..it has a blaster 240cc big bore air cooled top end married to the crank case inducted bottom end boyessen dual reeds 30mm lectron carb and wr200 fmf pipe. Off throttle is quite flat and slow tight stuff gives the clutch hand quite a work out. The mid and top end is opposite comming on hard with light switch delivery.. which makes it hard work.. im happy to move the power in favor of the bottom end .any mods you can suggest would be great to try..was even thinkkng of a early honda style exhaust pv set up..lol


Offline sleepy

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Re: improving bottom end power
« Reply #1 on: April 01, 2018, 12:09:37 AM »
Without knowing all the porting details all I can suggest is to lengthen the header pipe to increase to the tune length of the pipe. Try 100mm if you can make it fit. A bit more timing advance might help if it's not already on the edge. Also try lowering the barrel and spacing the head up the same amount to bring back the port timing.

Offline 80-85 husky

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Re: improving bottom end power
« Reply #2 on: April 01, 2018, 08:34:03 AM »
try leaning the needle 1 clip and see if this smooths the hit. does it feel like its dragging a bit before the top end rush? it may be a little rich on the bottom. you could try dropping the pilot jet 1 unit as well as get the airscrew out to 1.5 turns.

check the float level is right as well.

packing the muffler with steel wool instead of glass can also give more bottom end.

with the mods to the bike, its hard to make any simple suggestions without going "mechanical"as sleepy suggested.

Offline shelpi

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Re: improving bottom end power
« Reply #3 on: April 01, 2018, 10:48:22 AM »
thicker head gasket, place weight on the flywheel,

Offline skypig

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Re: improving bottom end power
« Reply #4 on: April 01, 2018, 02:37:08 PM »
Smaller carby?

Offline Kane Mcguire

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Re: improving bottom end power
« Reply #5 on: April 01, 2018, 08:59:25 PM »
When you say off the bottom is quite flat, I would start with jetting and changing ignition timing if you can. Its good to make sure what you have is correct before trying different carbs and pipes etc. I got a bike a lot better first with jetting etc and then I added to the header pipe.

Offline twinrock

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Re: improving bottom end power
« Reply #6 on: April 02, 2018, 08:31:49 PM »
Thanks guys.. it will be difficult to lengthen the header pipe. I have advanced the timing by adjusting timing plate.
As far as the carb goes its a lectron which has a metering rod..not jets as such..i have noticed these carbs seem to loose bottom end response dispite claiming the opposite. I will try a different carb .i have heard of lifting the cylinder thicker bace gasket.?.the bike has almost 170psi compression . I had not heard of steel wool in muffler before..any one used reed spacers to increase bottom end

Offline John Orchard

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Re: improving bottom end power
« Reply #7 on: April 02, 2018, 09:19:29 PM »
A thicker base gasket, or head gasket will do the opposite to what you want.
Johnny O - Tahition_Red factory rider.

Offline twinrock

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Re: improving bottom end power
« Reply #8 on: April 02, 2018, 09:51:25 PM »
Yeah i have just been researching base gasket thickness.. now i think about it makes perfect sence..it does feel like a porting or pipe issue..maybe i can run a thinner bace gasket to lower the exhaust port ill check the head squish to make sure i have enough tollerance..also with that kind of compression should i be running as high octane as possible..would that make much difference thanks again

Offline sleepy

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Re: improving bottom end power
« Reply #9 on: April 03, 2018, 09:41:20 AM »
Thinner base gasket will only make a marginal difference as you will only change the port timing by a small amount. Increasing the CR will help the bottom end to a point but without knowing were the squish and and ratio are now I can't comment but can say that the octane of the fuel will not change the power in a low compression engine, octane is only the resistance to knock and has nothing to do with the calorific value of the fuel.
It is possible to machine the bottom of the barrel to reduce the port timing but a thicker head gasket or re-machined head is needed to get squish and CR back to were it should be.
Pity you can't lengthen the pipe as it would make the biggest difference, sure you can't add a bigger radius bend and push it sideways and then re-join.

Offline evo550

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Re: improving bottom end power
« Reply #10 on: April 03, 2018, 06:59:23 PM »
Sounds like you've mixed and matched a little to much.....

Offline Butcher

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Re: improving bottom end power
« Reply #11 on: April 03, 2018, 08:55:29 PM »
Im not real smart, but a dt200 is never gunna have a lot of bottom end. If you ride a lotta tight stuff, lower the gearing....

Offline twinrock

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Re: improving bottom end power
« Reply #12 on: April 03, 2018, 10:13:54 PM »
Yeah..but mixing and matching is what i enjoy..i ride with a mate who has a basically stock dt..its much easier to ride in the very slow tight stuff..due to the power valves..but after 1/4 throttle my bike runs away easily..its also feels considerably lighter..less top heavy to be more specific as it has no radiators plumbing fluids and protective frames and guards..so pros and cons.. my idea behind the engine was a nice simple smooth air cooled engine with oil injection With fun power..thanks for your help it has given me some direction

Offline Momus

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Re: improving bottom end power
« Reply #13 on: April 04, 2018, 12:25:59 AM »
Put a D slide PWK carby on it. 28/30/32. Will be night and day over the Lectron.

Offline OverTheHill

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Re: improving bottom end power
« Reply #14 on: April 04, 2018, 09:18:23 AM »
My idea, good or bad. Tune it with the pipe. Bit of a story but had an IT400 motor in a DT250 mono frame & someone had over ported it to 192 degrees on the exhaust. Was useless--ok at idle up to 1/4 then flat till 3/4 then it went mad. Was 'so' bad i add 100mm to the header & being my lucky day it totaly fixed it. But changing tact a bit on my AG100 grasshopper [assgroper] they have a good cylinder to modify but come with a tiny 20 or 22mm carb [same outside diameter as a 28. In my wisdom i fitted a 28mm. Went good up top but lost its sharp bottom end. So maybe two different ideas to think about. Cheers. ps, like what ya doing though. Mix N Match--fun times.