XRR needs more topend


53 replies to this topic
  • Krannie McKranface

Posted November 22, 2007 - 06:24 AM

#21

The Edelbrock has no main jet, only the needle is replaceable. Do you know which needle is in your Eddie? Have you tried adjusting the needle height with the external adjuster?


Yes, I know theres no main jet, I just meant tuning it 'like' putting in a larger main.

I am fiddling on saturday.........

  • Potts228

Posted November 22, 2007 - 09:33 AM

#22

I changed to the Pro Circuit complete system from the FMF Power Bomb system and now have top end! We gained about 7mph on top switching to the PC.

  • Krannie McKranface

Posted November 22, 2007 - 12:05 PM

#23

I changed to the Pro Circuit complete system from the FMF Power Bomb system and now have top end! We gained about 7mph on top switching to the PC.


That's what I am talking about. What about the bottom end, did it suffer? I would imagine with the Edle or similar pumper you would loose no 'basement' torque.

  • weskc35k

Posted November 22, 2007 - 01:02 PM

#24

BBA it's all mild stuff but it adds up.
Krannie it's a 650 thumper it may have some basement potential.
It's never gonna rev like the X but gear it for "THE MEAT" and it'll fly.
I want an Edy as well as some headers but it's running OK as it is.

  • Thumpmeister

Posted November 23, 2007 - 10:38 AM

#25

I remember reading somewhere that the edelbrock doesn't do as good in the top end as the stocker does. Something about the pump on it? Also, I remember reading that putting a higher compression piston in will add a lot more torque on bottom, but will actually take away a little on top. I read this in dirtbike a number of years ago (like 5+), but just thought it was worth mensioning...

As for top end speed, I know my pig does over 100... Before I did the cam, header, and airbox mod, I could do 95+ (speedo stopped at 95) on stock gearing. Now since I have had the head machined, stg 1 cam, full white bros exhaust, and drilled airbox cover, I know my pig will do over 100 easy.

  • Krannie McKranface

Posted November 23, 2007 - 02:55 PM

#26

I remember reading somewhere that the edelbrock doesn't do as good in the top end as the stocker does. Something about the pump on it? Also, I remember reading that putting a higher compression piston in will add a lot more torque on bottom, but will actually take away a little on top. I read this in dirtbike a number of years ago (like 5+), but just thought it was worth mensioning...

As for top end speed, I know my pig does over 100... Before I did the cam, header, and airbox mod, I could do 95+ (speedo stopped at 95) on stock gearing. Now since I have had the head machined, stg 1 cam, full white bros exhaust, and drilled airbox cover, I know my pig will do over 100 easy.


Well, I can go 80ish according to my speedo. Maybe it's out of calibration?

  • weskc35k

Posted November 23, 2007 - 03:26 PM

#27

Thumpy you lose nothing up top with the Hi Comps on a 650 but it gives a heap of torque down low.
I believe what you are on about is cranking losses with Hi comp stuff CRF's run a bit of compression and still rev to the moon.
What did you have done to the head?

  • scalejockey

Posted November 23, 2007 - 03:26 PM

#28

on my trail tech speedo mine says 85 on a dirt road 93 on pavement with 14-47 gears

  • Billahjack

Posted November 23, 2007 - 05:18 PM

#29

Cam and Header are the easy way to go if you want more top end. I have a Stage 2 sitting around. I ended up using the HRC instead. PM me if anyone wants the stage 2.

  • Krannie McKranface

Posted November 23, 2007 - 05:31 PM

#30

Cam and Header are the easy way to go if you want more top end. I have a Stage 2 sitting around. I ended up using the HRC instead. PM me if anyone wants the stage 2.


What's the difference between a Stage 2 (hotcams?) and a HRC cam.
I AM interested.

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  • weskc35k

Posted November 23, 2007 - 09:32 PM

#31

The HRC cam has less lift and duration than a Stage 2 Hot cam but more than a Stage 1 for duration but lift i don't know.
Just do it.

  • Thumpmeister

Posted November 24, 2007 - 01:58 AM

#32

Thumpy you lose nothing up top with the Hi Comps on a 650 but it gives a heap of torque down low.
I believe what you are on about is cranking losses with Hi comp stuff CRF's run a bit of compression and still rev to the moon.
What did you have done to the head?


I did a top end on my pig a couple of years ago because I had sucked a little sand into the airbox, and obviously through the motor. I replaced the piston, valves, valve guide seals, etc... I was thinking of going with the high comp piston, but I had read that article a number of years ago about losing some top end, so I didn't do it.

I had some head work done on my pig when I did the top end. There is a guy that runs a racing shop near where I live called BBRP (Brian Billings Racing Products). I asked him what he could do to my head. I was thinking of doing a port and polish, but I decided against it after reading some guys have actually lost some top end from doing it. The guy didn't really give me the logistics of what he had done, all he told me is that he 'machined' the head, but didn't do the port and polish. I think he might have just done a valve lap, but after I got it back, it definatly had more work done to it than just a valve lap.

I was thinking of goin with an HRC cam and a hi-comp piston if I ever have to do another rebuild, or if I ever want to. So far, power isn't really an issue. My buddy was following me in his Tacoma at the time, and he said he was doing 90, and I was pulling away from him. Plus, the speedo I had on was bouncing at 95.

  • Potts228

Posted November 24, 2007 - 01:00 PM

#33

That's what I am talking about. What about the bottom end, did it suffer? I would imagine with the Edle or similar pumper you would loose no 'basement' torque.


By the seat of the pants there was really no loss in low end. The 650 is such a torque machine anyway.

Our GPS showed a top speed of 98mph with 15/47 gearing and a HRC cam.

  • Krannie McKranface

Posted November 24, 2007 - 02:51 PM

#34

I turned the needle adjuster in 2 clicks richer, and changed out the K&N (ugh) for the UNI filter.
- Noticable improvement in everything: acceleration, top-end, hanging idle, and decelleration popping; all changes where slight, but evident.
- I think two more clicks rich might do it (have'nt counted total number of clicks yet).
- On the 118fwy, slight uphill, into the wind, I got 89mph wide open. That' probably 4-5 more mph (hard to tell what kind of change in top mph with the high winds...).

Also, I put some 'gunk' on strategic places on the bike that just wouldn't get clean, from the previous owner's chain lube (probably Bel-Ray or similar: that stuff is like glue, and after 7 years, it is like epoxy). I got 90% off with very little elbow grease. It will take some serious parts removal to get it really clean.
Amazing how much better the bike looks just looking clean and stock.

  • Thumpage

Posted November 24, 2007 - 08:54 PM

#35

Krannie,

Thumbs up. I think you have basicly gotten to the bottom of your problem. Before now, I thought when I had gotten the chance, I was going to tell you that it appeared that your flat top-end was associated with your hanging idle situation you asked about in your other thread. Both of these problems really lean towards a lean condition, heh,heh pardon the pun.
The whole talk of a hotter cam and such is not the solution to what you have had going on with your bike. A cam would certainly give the bike more pull and topend power over what the bikes current potential is but as said is not the solution to what is/was currently going on.
What made your lean condition even more pronouced is that you were using a K&N. I have used the K&N myself for awhile along with a UNI. I have found that the click adjustment setting needed with use of a K&N can be required to be richer in comparison to a foam filter if you have holes in your sidecover. Some bikes and mod setups may vary.
In short, it appears your needle click adjustment was set too lean as well as a freerer flowing K&N filter contributing to an even leaner condition. These two factors together could very well be your bikes problem.

As a side note to what Thumpmeister brought up;
It has been said by the Baja Honda team,(from what I have read) that in their experience, the higher comp piston does not allow the XR650R to rev out as much or maybe as cleanly versus the stock compression piston when both are used with the HRC cam. Honda was reported as using the HRC cam and stock piston for longer, higher top speed races for rev out and used the HRC cam & HRC high comp piston for desert races where the course was a bit more transitional in speeds. It appears the high comp piston does add additional power pull but I guess does not provide the same kind of over rev.
As an additional note, when the top speed wars took place a few years ago out at the dry lake beds, the Honda team switched from a full HRC kitted bike to another one of their bikes with the HRC cam and stock piston. That was the bike that ran better/faster on flat out speed runs. I still have that magazine article tucked away somewhere.

  • weskc35k

Posted November 24, 2007 - 09:13 PM

#36

Rubbish they don't use the HRC all the time as they worry about fuel quality in Mexico.
There is no pumping losses in a motor that only revs to 8 or 9k,your story is not quite right.
This is HS.

  • Krannie McKranface

Posted November 24, 2007 - 09:22 PM

#37

Rubbish they don't use the HRC all the time as they worry about fuel quality in Mexico.
There is no pumping losses in a motor that only revs to 8 or 9k,your story is not quite right.
This is HS.

:thumbsup: :busted:

  • Billahjack

Posted November 24, 2007 - 09:23 PM

#38

I'm getting 103 MPH (Garmin GPS) on flat roads with HRC, moriwaki exhaust, knobbies and 14/48 gearing. Its hitting the rev limiter at that speed. I'm at about 2700 ft Elevation. My buddy with 15/48 gearing, same tires, stock cam, FMF Powercore4 slip-on, stock header easily beats me up to about 6-7k RPM when I start to catch up. I think the tubes on the Moriwaki are a little big for stock compression.

HRC piston is aggressive for lower octane fuel on this motor. Sometimes people mill off the bump in the middle of the HRC piston to slightly drop the compression. I think Honda reccomends race gas only just to be safe, but I have heard others running 91-93 octane alright.

Not sure what he meant about pumping losses, as that can mean alot of things such as volumetric efficiency at certain RPM ranges from cam lift/duration/valve size/port size/exhaust restriction/intake restriction to cam overlap and low rpm operation.

  • weskc35k

Posted November 24, 2007 - 09:29 PM

#39

Just my opinion,my bike is faster with the higher compression .
It does 112 mph on hard dirt roads on the GPS at 15/46 must need a lower comp piston.
I don't run a speedo any morebecause most of the time on dirt roads i just don't want to know how fast i'm going
My apologies.

  • Krannie McKranface

Posted November 24, 2007 - 09:32 PM

#40

Krannie,

Thumbs up. I think you have basicly gotten to the bottom of your problem. Before now, I thought when I had gotten the chance, I was going to tell you that it appeared that your flat top-end was associated with your hanging idle situation you asked about in your other thread. Both of these problems really lean towards a lean condition, heh,heh pardon the pun.
The whole talk of a hotter cam and such is not the solution to what you have had going on with your bike. A cam would certainly give the bike more pull and topend power over what the bikes current potential is but as said is not the solution to what is/was currently going on.
What made your lean condition even more pronouced is that you were using a K&N. I have used the K&N myself for awhile along with a UNI. I have found that the click adjustment setting needed with use of a K&N can be required to be richer in comparison to a foam filter if you have holes in your sidecover. Some bikes and mod setups may vary.
In short, it appears your needle click adjustment was set too lean as well as a freerer flowing K&N filter contributing to an even leaner condition. These two factors together could very well be your bikes problem.

As a side note to what Thumpmeister brought up;
It has been said by the Baja Honda team,(from what I have read) that in their experience, the higher comp piston does not allow the XR650R to rev out as much or maybe as cleanly versus the stock compression piston when both are used with the HRC cam. Honda was reported as using the HRC cam and stock piston for longer, higher top speed races for rev out and used the HRC cam & HRC high comp piston for desert races where the course was a bit more transitional in speeds. It appears the high comp piston does add additional power pull but I guess does not provide the same kind of over rev.
As an additional note, when the top speed wars took place a few years ago out at the dry lake beds, the Honda team switched from a full HRC kitted bike to another one of their bikes with the HRC cam and stock piston. That was the bike that ran better/faster on flat out speed runs. I still have that magazine article tucked away somewhere.


Thumpage
I agree: getting the bike to run as cleanly as possible is the first order to getting the most out of the motor. I am not one to throw money at problems expecting a solution.
I'm one of those guys that can feel the difference in gas brands/octanes, when all around me say I am crazy. When I started with two-strokes, I matched, ported, and polished motors for me and my friends, and learned quickly that everything has a compromise when you try to go with 'more'. I know that getting the Edle dialed in will give me the most of what i want right now: 'better' power, opposed to 'more' power.
Having said all that, getting a bit more top end without having to gear up would be nice. I really like the stock gearing for dirt, but would like to accelerate to 80 mph as quickly as possible, as LA fwys are nutty to be on without superior power.
So, I plan to do these things, in no specific order, to get the bike 'better' before I go 'bigger':
- learn the edle's tuning and go as rich as is practicle
- replace my rear blown shock, and go with heavier springs
- get the front and rear shim stacks redone by ESP
- replace plastics as they become (cheaply) avialable on ebay
- find a reasonably priced full exhaust (I really think the stock header is part of the problem with over-rev)
- get a comp/speedo (I want to see revs)
- new chain and sprocket
- get the valve train freshend, do a bit of home port/polishing, and while I'm at it, try a new hotte cam.

I ride the thing almost everyday right now, and do an occasional 'questionable' trail ride near my Chatsworth home. I don't think I will have the confidence to do a 'real' ride till the rear boinger is fixed (pretty boingy now).
-





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