Listen to this, and tell me what you think.

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StreetLimitz89

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Oct 8, 2010
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okay, here is the scneraio. 1991 honda cr 125R 1.0mm big bore, current jets is a 172 main, 52 pilot and a R1469N needle in clip postion 1 ( Closest to the taper ) this video was shot when the bike had a 152 main, 52 pilot, and the same needle in the same position. the bike IS running, but by the video you WILL be able to tell Its running Horribly, the sound IS off on the video BUT you can Still hear the gurgle it makes getting into the top end.
around 15 seconds you can hear the noise or " Gurgle its making.

<iframe title="YouTube video player" class="youtube-player" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/vdPse498aaw" frameborder="0" allowFullScreen></iframe>
 
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StreetLimitz89

Member
Oct 8, 2010
40
0
okay, what needle would be a slight bit richer im looking at a BUNCH of different kinds, and the letters deg del cel idk what they all mean, i need a R1468N or atleast a semi close one to a R1468N what letters should i look for?
 
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Chili

Lifetime Sponsor - Photog Moderator
Apr 9, 2002
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Be hard to tell anything unless it was being ridden like a 125. All I got from that video is it sounded like it wanted to go but is loaded up from being short shifted and lugged around.
 
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EncyclopediaRonnie

Member
Nov 8, 2010
142
0
Chili said:
Be hard to tell anything unless it was being ridden like a 125. All I got from that video is it sounded like it wanted to go but is loaded up from being short shifted and lugged around.
Click to expand...

rev it up give it a handfull and hold it by the sound if anything your a bit rich down low and backing of the juice as its about to make majic happen
 
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StreetLimitz89

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Oct 8, 2010
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see weve tried being light on the throttle, and it just dosent seem to do anything different i wonder if maybe its to lean on the bottom end? could that be a possibility?
 
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Chili

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Apr 9, 2002
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StreetLimitz89 said:
see weve tried being light on the throttle, and it just dosent seem to do anything different i wonder if maybe its to lean on the bottom end? could that be a possibility?
Click to expand...

I'm confused by saying you tried being light on the throttle is this video your version of revving it hard? If so you and a 125 weren't meant for each other. The rider in that video let's off the throttle and shifts pretty much anytime the bike get's anywhere near the powerband.
 
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StreetLimitz89

Member
Oct 8, 2010
40
0
well he was shifting like that for the most part cuz the new top end only had about 45 mins on it soo yea, ill make another video with a regular rev no load, and then ill take one of actuall riding it will rev up fine, in neutral, but when it comes to actually riding it just sounds like that. we're at a loss and a state of MASS confusion.
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
8,129
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Merrillville,Indiana
If that engine has ran 5 minutes, its broke in. Now learn to ride it. It never got into the power band. The first time will need clearing it out, wind it up tight, and do not back off. Riding in the winter, in the street, with no helmet? Do you know Skippy the ninja mechanic? Vintage Bob
 
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StreetLimitz89

Member
Oct 8, 2010
40
0
lmao, its not doing nothing. ive tried holding it wide open, but it just dosent seem to pull, the bike has ran for a totall of over 3 hours now and it STILL is doing the same thing. where do i go next?
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
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Merrillville,Indiana
Take the gas tank and pipe off, and turn the bike upside down. Slowly turn the engine over with the plug removed. Is it full of fuel? Check the timing, and double check the rotor key is not sheared. Replace the float valve, and set your jetting to the book for altitude and temperature. Then try jetting it.
 

Rich Rohrich

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StreetLimitz89

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Oct 8, 2010
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0
 

whenfoxforks-ruled

Old MX Racer
~SPONSOR~
Oct 19, 2006
8,129
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Merrillville,Indiana
Of course the ignition could have issues and cause this also. The wrong spark plug to a wire in the magneto or cdi box going crazy? A good multi tester and the shop manual. But, I do believe it is possible to fill the cases with fuel, and not clear it out/blown a seal someplace? The float valve would be the culprit of that!
 
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StreetLimitz89

Member
Oct 8, 2010
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yea the carb been totally rebuilt float, float valve the pointy looking thing (=> yea that thing...... jets the only thing we have not changed yet is the slide needle. ive been told use a certian one, or atleast "try" the certian one, but since the Keihin PJ carb is discontinued finind parts for it has been a trick, i was thinking about swapping carbs to a fcr or maybe a pwk, but idk if it would be a "plug n play" swap because im thinking, a newer carb, might be easier to find the right parts for it but i will def try the ignition thing and see what results i get from there. .


Thinking back on it now, when i got the bike, the little piece that has teh 2 screws holding it on the crankcase the tiny magnet, was loose i tightened it up but never thought about maybe it moved ill def look at it today and see what i can come up with.

Thanks again.
 
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StreetLimitz89

Member
Oct 8, 2010
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okay i know this sounds retarted, but i know on my drag car,, when i bored the engine i had to change the timing i had to retard it 1 degree, would it be the same on a 2stroke?
 

Rich Rohrich

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StreetLimitz89 said:
jetting isint an issue,
Click to expand...

:bang: :bang: How stupid of me to think otherwise!
 
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StreetLimitz89

Member
Oct 8, 2010
40
0
Rich Rohrich said:
:bang: :bang: How stupid of me to think otherwise!
Click to expand...
ive got main jets ranging from 150 all the way up to 210 and pilot ranging from 30 up to 70 so ive got quite a collection as of right now.
 
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EncyclopediaRonnie

Member
Nov 8, 2010
142
0
hey dude so if you are animent its not jetting and you just did a top end build what pipes does it have ???? when was the silencer last re packed and has the chamber been cleaned out you may have a verry poor exaust system letting you down when you try to get on band
 
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helio lucas

~SPONSOR~
Jun 20, 2007
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do you rebuilt the top end with the help of the service manual?
exhaust valve operation and timing ok?
new spark plug?
silencer packing, as indicated before?
air filter correct and lightly oiled?
fresh fuel mix?

no rag left in exhaust or inlet? maybe a mouse nest?!?!?!?
 
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StreetLimitz89

Member
Oct 8, 2010
40
0
Vintage Bob, YOU ARE the man!!! :cool: i adjusted the timing i took the entire stator off cleaned all the points that make contact with the crank case and adjusted the timing ever so slightly and OMG! the bike rips now its still got a bit of a top end "burp" i would say but i have a feeling its because the needle is wrong size and the pilot jet is to small but Vintage Props to you GREAT advice!
 
Last edited:
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dirt bike dave

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May 3, 2000
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StreetLimitz89 said:
its still got a bit of a top end bog but i have a feeling its because the needle is wrong size and the pilot jet is to small
Click to expand...

Congrats on getting it running strong. But FWIW, the pilot jet is not going to have any effect on a top end bog. That's main jet territory.

Never did a 1mm overbore, but in my experience overbores like leaner jetting than the standard bore, everyting else being equal. Something about sucking in the air harder.

Another thing to consider is the porting might not be optimized for high revs with the new bore size. When I took a KDX200 to 240 it lost lots of rev on top.
 
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StreetLimitz89

Member
Oct 8, 2010
40
0
well now we've run into another problem lmao, the left radiator seems to be leaking =[ anybody know where i could get a good condition used one for cheap? or about what the average price is to have it repaired? it looks like the top ended up separating one way or another, im not sure how or why, but it did =/
 

Lorin

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Jun 25, 1999
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not sure of your location, but that jetting (by the numbers) would be very rich in my area. Pilot usually ends up in the low 40s (40-42), with the main being around the mid to upper 150's. This is mainly on 250's, but my 500 didnt even have a main that rich.
 
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