[jsnotech]

After doing a preventive rebuild with new top end and switching out the "X" cam for a "R" cam (of the same year 2008. My head pipe is getting RED hot fairly quick. It never got RED hot before.

Lean?

I'm using a JD jetting kit and didn't make any changes during the rebuild. I'll update the post with the JD needle type and clip position asap.

more details
4,000'-6,500' asl
cut sides of the air box and top removed
smog equipment removed and blocked
FMF mega bomb head pipe and Q4 tail pipe
RD flex fuel screw, don't recall how many turns

I have not done the pink wire mod, yet

Thanks

[JimDirt]

How long are you letting it sit and idle ?? , and how long did the bike sit ??(with the same gas in it) , if it sat for more than a month i would guess the pilot jet is clogged partially , this will give a lean condition at idle where it was not present before , you need to confirm the jet is not clogged , and also , when you rev the bike does it pop thru the muffler ?? , this is a sure sign the pilot is clogged

If this is the case , you can either clean the pilot jet with the correct tool , or just replace it as they are not expensive

[jsnotech]

Just a normal, choke on, start and warm up for 2 minutes. It idles kinda high with the choke on. It won't idle well with the choke off. Starving for fuel? The head pipe almost instantly gets full RED hot.

So, I had a local dealer do the engine work. They found the pilot jet to be clogged during a fire up and check out process. They cleaned it. It was delivered to me in this condition with recommendations. They recommended I go to a larger pilot jet. A 48? They also played with my RD flex air screw. They said it didn't make a difference during their attempts. The idea was to go to a larger pilot jet and use the RD flex air screw to dial it down if it ended up a bit too rich with a 48.

It ran perfectly for 8 years and over 200 hours with the previous jetting and setup as an "X". Before I go chasing my tail in the jetting world now that it's an "R". I was looking for more opinions here before I just go with story #1.

[JimDirt]

This is a jetting guide made by one of the members here (leardriver) that is a carb expert and works with one of the best carb guys in the business

Jetting Guide for Main Jet:(pilot 45) CRF450R/X

Sea level....165
2000 ft.......162
4000 ft.......160
6000 ft.......158
8000 ft.......155


Temperature/Elevation:
One main jet size (up/down) for every 2,000 feet or 25 degrees in temp.

He says that in most every situation a #45 pilot jet is good

What i would question with the dealer is

When they tried adjusting the fuel screw , what were the adjustments and findings ??

If they needed to turn it in to less than 1 turn then the engine is too rich , if they need to turn it out to more than 3 turns , its too lean

The fuel screw at about 1 1/2 - 1 3/4 from all the way in (gently , do not force it tight , just gently seated) should show improvements or at least a change in idle and RPM's

Did the dealer check/replace the O-Ring for the fuel screw ?? , if this is damaged the bike will run lean and not tune worth a crap

Did the dealer try replacing the pilot jet , to see if it cured the issue ??? , if not , WHY ??

Did the dealer mention what position the clip on the needle was ?? , it should be around the 4th position from the top (richer)

So check your jets and see if they are in range of the chart for your elevation , either way , red hot means lean

Also , i am assuming they had the carb removed , if so , was the Hot Start lever and Plunger checked to make sure they were free and functioning properly ?? , as a stuck hot start plunger or cable could cause a lean condition

I would not go to a #48 pilot , because you already know it ran before with the prior jetting

What exactly was the "prior" jetting ??

Main Jet size ___ (original i would guess was a 142)

Pilot Jet Size __ (should have been and stay a #45)

Fuel Screw Position (it should have been between 1 1/4 to 1 3/4 turns out)

Needle Clip Position (it should have been on the 3rd clip position from the top of the clip , change to 4th)

My guess is the O-Ring for the fuel screw is bad or the old one was not removed when the new R&D Flex Jet was installed , this would create a lean condition and fuel screw adjustments would not be anywhere near close to correct and you would have a constant lean condition that you can't tune out of it

Or the Pilot jet is still clogged and needs to be replaced (they are under $10) with a NEW one

[jsnotech]

The fuel screw was installed in 2011. I don't think they messed with the fuel screw O ring. No discussion of the hot start equipment.

The dealer said they tried adjusting the fuel screw all the way out and that didn't make it better. That's was the reason for a suggested increase in size of the pilot jet. Then using the fuel screw to dial it down. As if the 45 is borderline too small and the next size up, a 48, could be a bit too big but would be used at/near the lowest/tightest setting of the fuel screw. They choose not to experiment with the carb because I was the type of customer who asked them to do a specific job and I provided the parts. They tried to work with what they had and even gave it a few "free" hours in doing so. They pulled and found the pilot jet to be clogged. They cleaned the pilot jet and tried some more. They stopped there and didn't touch any other carb items. I didn't have the time to do the rebuild. I would have done it myself normally. 1st time using a shop/dealer for anything I consider some what easy. I'm happy with their work (I think?). The carb is on me.

so here's my settings from 2011 that were posted in the jetting database here on this message board. Nothing has changed except wherever the fuel screw is now after the dealer turned it somewhere, the "R" cam, and new piston/rings. When the top end was pulled apart. They questioned me as to why I was rebuilding it. It looked almost new. The bike had over 200 hours on it was my reason.

Year: 2008
Elevation: 4300'asl-8500'asl
Temperature Range: 46dF-90dF
Smog (AIS): applied racing block off
Airbox Modified Top: yes
Airbox Modified Sides: yes
Backfire Screen: removed
Air Filter: twin air backfire w/ stock cage
Pilot Jet: stock
Main Jet: 170
Needle: JD red
Needle Clip Position: 4th
Fuel Screw Type: R&D flex
Fuel Screw Setting: 1 1/4
AP Modified: no, it is an 08
Leak Jet: stock
AP Cover: stock
Exhaust Type: FMF
Exhaust Modified: mega bomb & Q4
Pink Wire Modified: no

I don't recall why the main jet is so large?

[JimDirt]

From your settings , i would say the Main jet has been too large , it should be around a 160 , and i still believe the Pilot jet is partially clogged , and i would be real concerned about the O-Ring for the Fuel Screw , since the fact that they could turn it all the way out and not have a change , means to me that the O-Ring is not doing its job and there is a constant vacuum leak

What i would suggest is to do a complete carb removal and rebuild , consisting of the Floating Valve Seal http://www.crfsonly.com/catalog/product ... ts_id/3687 , a Fuel Screw Rebuild Kit http://www.crfsonly.com/catalog/product ... ts_id/2158 , and a NEW Pilot Jet (#45) http://www.crfsonly.com/catalog/product ... ts_id/4975 , and while its apart , make sure the Hot Start Plunger is working properly and free and that the HS cable is not sticking , since everything is pointing to a lean condition so any place you can draw vacuum or suck air is a suspect

PM leardriver , as he is the resident carb guru , but from what i am reading , you either have a blockage (internal in the carb) or a air leak , and jetting larger is not going to solve the issue , its like putting a stick in a tire puncture , it may slow down the leak , but there is still a hole in the tire and its still leaking

No matter what , the carb needs to come off and be completely inspected , if the fuel screw O-Ring is even slightly deformed , it will cause issues , you need to look into the hole once you remove the fuel screw and O-Ring and make sure there is no remaining O-Ring from the old screw , or that the O-Ring that came with the flex jet has not been compromised , as well as even the slightest of blockage in a pilot jet will cause starvation issues and tuning difficulties

I am far from a carb expert , but this is most likely the issue

[jsnotech]

I agree on the fuel screw o ring.

I'm planning on buying a new o ring and (2) new jets. A 45 and a 48 just to experiment with. $10 each is doable.

I have experience with float valves and valve seats on other types of carbs. Usually brought to my attention due to flooding or overfilling of the carb bowl. That could go either way. Stuck closed (not likely because this machine starts and runs for more than a carb bowl's worth of gas) or partially open (starving the engine), not sealing/seating (flooding/over filling the carb bowl), and blocked (starving the engine).

Reviewing the jetting data base here. 170 is very popular along with the 165. Some even run 180+. I'll have to review the JD jetting kit instructions for more info.

I'm thinking it's simple because it did sit for a while (5 months?) between the last ride and the rebuild. A blockage is my first thought. Bad o ring might be likely after it was dried up and got twisted on during testing. Sunday will be tune and test day. I'll reply with the results asap.

[jsnotech]

Thanks for the ideas

[JimDirt]

Hopefully , you followed what i posted on the Floating Valve Seal , it is on the slide (shown in the link i posted) , not part of the float bowl (needle and seat) , that is what i was referring to ....just to be clear ......

Also , sitting for 5 months , with the issue of Ethanol in the fuel , which has a tendency to turn gas to crap in about 1 month , as you can drain the gas out of your tank and it will fire up your lawn mower and your car/truck , but these bikes will hardly start let alone run correctly with gas even 1 month old sometimes , but the longer the gas sits , the worse it gets in our bikes , so the jet or internal clogging would be highly likely thanks to the residue that Ethanol leaves as the gas evaporates , so start with the pilot jet renew(keeping it the #45 for now) , and reset the R&D Flex Jet to about 1 1/2 to start out with , and see if anything is better , doing just those 2 changes , then do 1 thing at a time till the issue is resolved if that does not solve it , so you know what actually worked

I would have posted sooner , but i was gone all day and just got home , as it was my moms 92nd B-Day today

[jsnotech]

Yes! One fix at a time.

Yep, I did see that floating valve seal part and checked out the link after I posted. I think I read your post kinda too fast the first time.

I was able to get the parts today. Jets were cheap and I had to buy a entire o ring kit for the FCR carb. Still not bad for an attempt this weekend. I'll try to get that diaphragm looking thingy (floating valve seal) if it is in stock locally just in case or use it for good measure anyways.

Thanks again.

[jsnotech]

holy cow! That valve seal from a dealer or OEM parts supply includes other items and cost $70-$80.

I hope that's not it. If so I'll just order the seal only from Ken for $13 and wait.

Fingers crossed

[JimDirt]

Yea , direct from Honda you have to buy the Seal and the Plate , from Ken you can get just the Seal

But while your waiting for it , you can still do the pilot jet and reset the Flex Jet adjustment , this should give a good indication if its going to run right or not , don't forget to put FRESH Premium in and flush the system before you go to fire it...

[jsnotech]

Well that was a lot of thinking and research.

Starting stripping the bike down to remove the carb. Drained the gas tank and removed it. Went to losen the intake boot between the carb and cylinder. It was already done for me! Maybe a source of an air leak? So I stopped there. I put my fuel screw all the way back in. Then went back to my original setting of 1 1/2 turns. Tightened everything back up. Fresh gas in the tank and fired it up. It ran with a fast idle. Faster than ever before. However no RED hot head pipe. Put on a helmet (yes even though "I was just going around the block")and rode around the block. The idle was way too high.

I broke out the trusty owners manual and looked up the carb section. I recalled where the idle screw/throttle stop was. A few turns out on that while it was running and BINGO! Running perfect. Grabbed a riding buddy and did 22 miles and 2 hours of slow tight single track. A perfect break in ride

[JimDirt]

GREAT !!!!

Glad to hear that its working , and you found the issue , it was pretty obvious that it was a lean condition , it was just a matter of locating the source

Adjust your idle to where it sounds right , then adjust your fuel screw in 1/4 turn , and listen to the engine , then do the same out , keep going each way till you get the highest idle without the engine dying or popping when the throttle is chopped , that is where you should leave the screw adjustment , then reset your idle only , to where its normal again , after this , the only adjustments you should have to make on the fuel screw is in or out 1/4 or so , to adjust for temperature changes or major elevation changes , and enjoy riding !!