ADVrider

Go Back   ADVrider > Bikes > Thumpers
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 08-17-2014, 04:49 PM   #1
fosjef67 OP
Adventurer
 
Joined: Apr 2014
Oddometer: 12
Question DR650 That will not REV out

So I have been fighting this problem for awhile. When accelerating hard (WOT) the bike cuts out around 5200-5800 rpms. If I fiddle with the throttle a little I can coax it past 6000 rpms and then the bike will rev all the way to red line.

Current setup is; air box intact with snorkel in place, FMF Q4 silencer, ground header weld, mikuni 142.5 main jet, air screw at 1.75 turns, slide drilled, stock needle, K&N airfilter.

I first started having this problem when I moved from the desert and reinstalled the air box side cover. I did have the dynojet kit in running a dynojet 155 main jet with their needle. Moved to a wetter climate, and decided to seal her back up (water crossings).

Initially I went down to the dynojet 150, which helped but bike refused to rev past 6000 rpms. Then removed the the dyno needle and went back to stock. All then all seemed well, except the problem resurfaced after a long ride just not as bad. Installed mikuni 142.5 main jet, problem still there but bike is up on power, 142.5 jet also fixed hesitation on initial throttle opening.

Has anyone came across this problem? I am starting to think that maybe its not a jetting issue. The bike does have 12,800 miles (with about 1/3 being off road time), so i am thinking maybe a worn slide. My other theory is spark related, I am running NGK dual ground plugs, and thinking maybe they are the issue (about 1500 on them currently). As I read on NGKs site that they can cause issues in some engines.

And no I will not be cutting up my air box or removing the snorkel, the bike has plenty of power and I prefer to keep the limited water intrusion protection.

Other than not reving past 5200 rps at WOT the bike is running great.
fosjef67 is offline   Reply With Quote
Old 08-17-2014, 04:59 PM   #2
acesandeights
Asperger
 
acesandeights's Avatar
 
Joined: Jul 2008
Location: So. Oregon
Oddometer: 3,469
You might call Derek at Motolab. He might be able to help you diag.
__________________
http://breakingbooks.wordpress.com
http://www.kenmarshallmetalworks.com/
I may not be Rainman, but I'm not stupid eighter. Like Bartek on a taco.

I'll die with this hammer in my hand.
acesandeights is offline   Reply With Quote
Old 08-18-2014, 07:19 AM   #3
fosjef67 OP
Adventurer
 
Joined: Apr 2014
Oddometer: 12
fosjef67 is offline   Reply With Quote
Old 08-18-2014, 07:57 AM   #4
lamotovita
Ageing Adventurer
 
lamotovita's Avatar
 
Joined: Oct 2007
Location: WA/AZ, USA
Oddometer: 1,344
Quote:
Originally Posted by fosjef67 View Post
So I have been fighting this problem for awhile. When accelerating hard (WOT) the bike cuts out around 5200-5800 rpms. If I fiddle with the throttle a little I can coax it past 6000 rpms and then the bike will rev all the way to red line.
What is "red line" on a DR650?
What year is your bike?
__________________
Beaten paths are for beaten men.
lamotovita is offline   Reply With Quote
Old 08-18-2014, 08:15 AM   #5
plugeye
mc caregiver
 
plugeye's Avatar
 
Joined: May 2007
Location: Garland, Texas
Oddometer: 3,321
why are you using a 142.5main?
i'd put the stock sized main in.
whats your mpg?
__________________
so what
plugeye is offline   Reply With Quote
Old 08-18-2014, 08:23 AM   #6
mcma111
Beastly Adventurer
 
mcma111's Avatar
 
Joined: Jul 2007
Location: San Francisco,Ca.
Oddometer: 10,869
To rich a main
__________________
Steve in SF

BMW's
58 R26
79 R100s
91 R100gs

87 Harley FXRS-SP ~ 06 KTM 625 SMC ~ 72 Honda CB750/915cc ~ 92 XR600/654cc ~ 95 XR650l/675cc ~ 03 CRF450r ~ 05 CRF450x ~ 02 XR650l/675cc ~ 86 YZ490 ~ 93 YZ80 ~ 93 XR650l Project
mcma111 is offline   Reply With Quote
Old 08-18-2014, 11:13 AM   #7
fosjef67 OP
Adventurer
 
Joined: Apr 2014
Oddometer: 12
Quote:
Originally Posted by lamotovita View Post
What is "red line" on a DR650?
What year is your bike?
The bike is a 2007, and red line is just over 7200 rpm.

Quote:
Originally Posted by plugeye View Post
why are you using a 142.5main?
i'd put the stock sized main in.
whats your mpg?
I am running the 142.5 main, becuase the stock size is a 140 and DR's are notorious for being set lean from the factory. So with the new exhaust and air filter, i did not want to lean it out anymore.
fosjef67 is offline   Reply With Quote
Old 08-18-2014, 11:18 AM   #8
plugeye
mc caregiver
 
plugeye's Avatar
 
Joined: May 2007
Location: Garland, Texas
Oddometer: 3,321
Quote:
Originally Posted by fosjef67 View Post
The bike is a 2007, and red line is just over 7200 rpm.



I am running the 142.5 main, becuase the stock size is a 140 and DR's are notorious for being set lean from the factory. So with the new exhaust and air filter, i did not want to lean it out anymore.
a stock airbox should run stock main jet. the exhaust & airfilter dont matter.
the lean from factory is the mixture, you have already adjusted it for 1.75 turns. not sure about the "drilled slide" feature...
__________________
so what
plugeye is offline   Reply With Quote
Old 08-18-2014, 12:52 PM   #9
fosjef67 OP
Adventurer
 
Joined: Apr 2014
Oddometer: 12
So, I am an Idiot.

For some reason I got it in my head that the Dynojet 150 main was roughly equivalent to a Mikuni 145. Which is why I went to a 142.5 to fix the stumble. Turns out I just went up a Jet size, which would explain way the problem persisted.

So next plan of action is to go back to the Mikuni 140, give her a good run to see were I am at, then start to fine tune the needle to coax a little more punch out of it.
fosjef67 is offline   Reply With Quote
Old 08-23-2014, 11:07 AM   #10
motolab
Beastly Adventurer
 
motolab's Avatar
 
Joined: Feb 2006
Oddometer: 2,131
Quote:
Originally Posted by fosjef67 View Post
So I have been fighting this problem for awhile. When accelerating hard (WOT) the bike cuts out around 5200-5800 rpms. If I fiddle with the throttle a little I can coax it past 6000 rpms and then the bike will rev all the way to red line.
RPM means revolutions per minute, so it is redundant to add an S at the end of the abbreviation unless you want to refer to a specific group of minutes the revolutions happened during.
Quote:
Current setup is; air box intact with snorkel in place, FMF Q4 silencer, ground header weld, mikuni 142.5 main jet, air screw at 1.75 turns, slide drilled, stock needle, K&N airfilter.
Slide guide wear is pretty much proportional to lift hole area, so drilling the slide will dramatically increase slide guide, emulsion tube and slide wear. Dynamometer testing I have performed also demonstrates that it causes a loss in hp at 1/4 opening and richens the mixture at 1/8 opening in not easily correctable manner.

The idle mixture screw on the BST40 carburetor is a fuel screw (out for rich and in for lean) rather than an air screw (in for rich and out for lean).
Quote:
I did have the dynojet kit in running a dynojet 155 main jet with their needle.
I don't recommend the DynoJet needle because:

1) It's the wrong shape and produces significant variances in mixture strength throughout the rpm range, specifically richer toward the bottom of the rpm range than toward the upper.

2) It's made out of stainless steel which means more emulsion tube wear than with an aluminum needle.

3) It doesn't use the white plastic spacer under the clip, which means the needle is not preloaded in the downstream direction, and will therefore be more prone to orbiting/otherwise gyrating inside the emulsion tube. It also means that the needle will not be able to pivot out of the way as the slide guide wears. Both of these factors equate more emulsion tube wear.

At 12,800 miles, the slide guide and therefore the emulsion tube is likely to be worn out. With the slide having been drilled and a dynojet needle having been installed, the likelihood is even greater.

There are six depressions in the face of the slide guide. Four of these are round. If the round ones are no longer visible, there is no need to look any further, the slide guide and emulsion tube are worn out. There are two more depressions that look like little parallelograms concentric to the bore adjacent to where the slide bottoms. These depressions are .020" (.51 mm) deep when the slide guide is new. Emulsion tube wear sets in somewhere around .010" (.25 mm) depth, and causes overly rich mixtures in the lower portion of the rpm range (see http://www.moto-lab.com/gallery/view?itemid=298 & http://www.moto-lab.com/gallery/view?itemid=299 vs.http://www.moto-lab.com/gallery/view?itemid=300 & http://www.moto-lab.com/gallery/view?itemid=301. How deep are these depressions now?

Is there any vertical grooving on the downstream side of the slide (see http://www.moto-lab.com/gallery/view?itemid=302 vs. http://www.moto-lab.com/gallery/view?itemid=304?
Quote:
Installed mikuni 142.5 main jet, problem still there but bike is up on power, 142.5 jet also fixed hesitation on initial throttle opening.
One size larger main jet than stock (i.e. the 142.5 you say you have installed) will only richen the mixture slightly (by ~1% CO). However, in order to produce a rich symptom, the mixture must be extremely rich (i.e. five or more jet sizes worth too large). Since we know that a 140 main is about the right size under normal circumstances, this indicates that the extra fuel is coming from somewhere else. Knowing the mileage, that the slide has been drilled, and that a dynojet needle had been installed, the prime candidate for the source of the additional fuel is a worn emulsion tube. Secondary candidates are high fuel level/overflowing carb due to a worn out float needle tip, dirty float needle seat, leaking float(s) {i.e. fuel inside the float(s)}, sacked out needle plunger spring, or misadjusted float height.

Regards,

Derek
motolab is online now   Reply With Quote
Old 08-23-2014, 11:09 AM   #11
motolab
Beastly Adventurer
 
motolab's Avatar
 
Joined: Feb 2006
Oddometer: 2,131
Quote:
Originally Posted by plugeye View Post
the lean from factory is the mixture
What else could it be?

Regards,

Derek
motolab is online now   Reply With Quote
Old 08-25-2014, 08:51 AM   #12
fosjef67 OP
Adventurer
 
Joined: Apr 2014
Oddometer: 12
Derek, thanks for the reply. Lots of useful information. I was unaware of the depressions in the slide guide, so I opened the carb up and all six are still there. The slide is scuffed some but nothing like the photos.

So here is where I am at. I switched back to the stock needle when this problem first surfaced. The slide was drilled only in the last 2,000 miles in an attempt to get a little better throttle response. This weekend I reinstalled the 140 main jet and the issues was still there, and bike was slightly down on power. So removed the carb gave her another deep down cleaning and reinstalled the 142.5 main jet, checked the float level (was spot on), and clean the fuel strainer in the carb inlet and fuel tank (nothing significant in either).

The floats are working properly, and if they were not closing properly I would assume that the bike would run poorly at anything less than WOT.

If emulsion tube was worn out I would also think that it would be an issue at anything less than WOT, as at WOT the main jet is the limiting factor.

At this point I believe the issues is either the drilled slide or on the electrical side (Timing advance?) of the house.

Also I just purchased a FCR-MX, (the price was right). So hopefully I will be able to determine if it is a fueling issue or electrical. (Recommendations on jetting the FCR-MX, based on my setup?)
fosjef67 is offline   Reply With Quote
Old 08-25-2014, 09:31 AM   #13
bwise904
n00b
 
Joined: Aug 2014
Oddometer: 2
could be your cold start enrichment circuit....
bwise904 is offline   Reply With Quote
Old 08-25-2014, 09:52 AM   #14
motolab
Beastly Adventurer
 
motolab's Avatar
 
Joined: Feb 2006
Oddometer: 2,131
Quote:
Originally Posted by fosjef67 View Post
Derek, thanks for the reply. Lots of useful information. I was unaware of the depressions in the slide guide, so I opened the carb up and all six are still there.
How deep are the depressions in the bottom corners of the slide guide concentric to the bore (the depth can be measured with the tail of a caliper)
Quote:
The slide is scuffed some but nothing like the photos.
If it has any vertical grooving at all, it should be replaced. The slide is much more wear resistant than the slide guide. Generally speaking, by the time the slide has vertical grooving, the slide guide is worn out (often the slide lasts several times longer than the slide guide).
Quote:
I switched back to the stock needle when this problem first surfaced.
By that time, the Dynojet needle is likely to already have done its damage.
Quote:
The slide was drilled only in the last 2,000 miles in an attempt to get a little better throttle response.
If the slide were not scuffed, the slide would be saveable by epoxying the extra hole shut (unless the existing hole has enlarged as well).
Quote:
This weekend I reinstalled the 140 main jet and the issues was still there, and bike was slightly down on power.
At what opening(s) was it down on power?
Quote:
So removed the carb gave her another deep down cleaning and reinstalled the 142.5 main jet, checked the float level (was spot on), and clean the fuel strainer in the carb inlet and fuel tank (nothing significant in either).
I would like to request that you use the terms "float height", or "fuel level", but not "float level". If you use the term "float level", it is possible to get confused between float height and fuel level, which is undesirable because when you increase the float height, you decease the fuel level (and vise versa). What is the float height set at, and what is the resultant fuel level?

Issues with the fuel strainer would first appear during sustained high rpm, large opening use. The symptom would temporarily subside if the throttle were closed/the rpm were allowed to drop for a sufficient amount of time (meaning that, if reinitiated, high rpm, large opening would be OK again for at at least a moment).
Quote:
The floats are working properly, and if they were not closing properly I would assume that the bike would run poorly at anything less than WOT.
It should.
Quote:
If emulsion tube was worn out I would also think that it would be an issue at anything less than WOT, as at WOT the main jet is the limiting factor.
A worn out emulsion tube most definitely affects WOT operation, but it influences lower rpm WOT operation more strongly than high.
Quote:
At this point I believe the issues is either the drilled slide or on the electrical side (Timing advance?) of the house.
I am skeptical about this being an electrical issue. Have you already checked for a clogged air filter, airbox inlet, or under diaphragm vent filter (btw. what does the filtration in this location consist of?)? How about the main air bleed jet, is that clean/clear?
Quote:
Also I just purchased a FCR-MX, (the price was right).
Considering the multiple reports of audible detonation on stock DR650s, and the high NOx levels recorded during dyno testing I recently performed on a DR650 with an FMF muffler with no insert, a cut airbox and the correct mixture, I would not recommend installing a carburetor that improves cylinder filling above and beyond what a cut airbox will provide, unless measures such as improving the exhaust flow above and beyond what an FMF with the insert removed can provide, reducing the squish clearance, pulling back the ignition timing, increasing octane (above 91 R+M/2), and/or reducing the compression were taken.
Quote:
(Recommendations on jetting the FCR-MX, based on my setup?)
Tuning an FCR can be very complicated and time consuming, even more so without a dynamometer with 5-gas analysis. Aside from idle and WOT, everything is on the needle. The reason that makes matters complicated is that the needle must therefore be the correct shape for 1/16, 1/8, 1/4, 1/2, and 3/4 openings to work correctly, whereas on most other carbs there are other circuits to deal with 1/16, 1/8, and 1/4 openings, meaning that only 1/2 and 3/4 openings must be correct via the needle. Two points define a line, and therefore a single taper at the right height can simultaneously provide the correct fueling for two openings such as 1/2 and 3/4. On the FCR 1/8 opening can be dialed in with the base diameter, and usually 1/16 is then correct. That leaves 1/4, 1/2, and 3/4 that must be correct on the taper, which may not be achieveable with the single taper needles available from Keihin's aftermarket division. There are multiple taper needles used in OEM applications, but it is very difficult to find them all (they are spread across multiple manufacturers), and only part of the letter code corresponds to the conventions established by Keihin's aftermarket division, so it's really difficult to tell what effect any given OEM needle will have by looking at the code. Some, but by no means all of these have been analyzed and the information has been put into the public domain by skilled and generous individuals. Unfortunately, there are often cases when neither Keihin aftermarket division, nor OEM needles will give the correct mixture at all openings. If someone like J.D. doesn't have a needle in his line up that fits the bill, a needle must be modified to work. Additionally, every FCR I've worked on had a significant slide over-travel problem, which must be resolved before it can be expected that the carburetor can be tuned properly.

Regards,

Derek
motolab is online now   Reply With Quote
Old 08-25-2014, 11:51 AM   #15
motolab
Beastly Adventurer
 
motolab's Avatar
 
Joined: Feb 2006
Oddometer: 2,131
Quote:
Originally Posted by bwise904 View Post
could be your cold start enrichment circuit....
If the cold start enrichment circuit were active when the engine was hot, that would indeed make the mixture too rich, however the effects would be most pronounced at lower rpm and negligible to nonexistent at higher rpm.

Regards,

Derek
motolab is online now   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 10:27 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014