[Tobbe]

Hi All

I think I am loosing my mind here.
I bought a CRF450R 2004 without know it's service history or how many hours it had run.
So I decided to do a complete engine rebuild, mostly as a precaution.

What was done:
New hot-rod stroker crank
New hot rod stage 3 cam
All bearing throughout the engine was replaced.
New high comp piston.
According to the previous owner, the valves were replaced not to long ago, so I took his word on that and kept the old valves and head. Currently kibble white SS valves installed.

The carb was completely torn down everything was cleaned, a JD kit was installed, all jets replaced, Acc pump mod done.

Complete FMF mega bomb system installed. Twinair air intake.

Fresh gas in the the tank.

New spark plug.

Now to my problem, It wont start. Nothing, stone cold dead. Not even a missfire.

Stuff already checked:
Using a motion pro ignition system tester. I have a nice strong spark with 6mm gap.

I have verified the cam timing, both two and three times. Also tried to move it one tooth in both direction to se how much of a difference it makes on the markings and then it looks way off. So the timing is definitely spot on.

Dubbel and triple checked the valve adjustments and they are within spec.

Compression test is showing about 80PSI.

I also have innovative afr meter installed to aid with tuning once i get it started. Before it actually fires I don't think the numbers mean much, but after kicking for a while the numbers start going down towards 14 between kicks and when kicking they quickly jumps up to 20 only to go down again. It doesn't say much, but I would be inclined to interpet it as it is getting some fuel as least.

I tried to find som starting liquid, but that turned out to be an impossible task as everyone tells me it's not available here (I live in Thailand). In a desperate attempt I tried to use butane instead. And not even that produced any sign of life. no misfire, nothing.

I am now starting to run out of ideas and really need some help to find out what is going on here.

Any suggestions?
I should also say that this is my first attempt at any major work on a bike engine.

[JimDirt]

Welcome to the site !!

The first thing i would try , is removing the spark plug and taking a tablespoon of gas and a long thin funnel (like used for a Automatic Transmission) and pouring it down into the cylinder , then replacing the plug , and try starting it , it should after a couple at most kicks , fire , this will tell you if you are actually getting fuel to the cylinder , as you seem to have eliminated most everything else

This will be a good solid starting point for diagnosing weather this is a Fuel issue or something else

I am assuming you did already check to make sure the AP is squirting ?? (and slightly missing the slide)

It is possible that your starting procedure might have to change , you may have to pump the throttle several times (4-8 ) to get enough fuel to feed the mods , the issue is , the more mods you do , the more finicky the bike will be in tuning , but basically you need Air ,Fuel ,Spark ,Compression and Timing to make the bike run , if all are in order , then its something you have done in assembly that is the issue , so its just a matter of eliminating each item completely and moving on to the next , since you did not mention that you verified its actually getting fuel to the plug , that is the first place i would start

[Tobbe]

JimDirt

Thanks

I tried with some fuel straight into the cylinder but that gave nothing, only did a few drops. Will try to increase the amount to a tablespoons worth tomorrow as it's getting late here now..

Actually I haven't checked that the AP squirt misses the slide, I will verify it tomorrow. I assume I should be able to see it with a mirror and flashlight without removing the carb?

[JimDirt]

You will obviously need to raise the subframe so you can see inside the rear of the carb , as that is where the squirt is , but no you will not need to remove the carb itself , just the airbox boot off the back of the carb , at which point you would be able to see directly into the carb and observe the AP squirting

[Tobbe]

JimDirt

ok, so I checked the AP squirt. and it looks like its missing the slide, I cant see that it hits and the backside of the slide remains dry. and I can see two nice squirts of gasoline going forward. However after trying it 4-5 times i did notice that the slide was getting wet on the underside.

I tried with a tablespoon of gas straight into the cylinder, and while it didn't clearly fire, it seemed like it got an extra revolution or two. so it might have fired once but wasn't able to sustain it.

Where to go from here?

[JimDirt]

OK , it is sounding like it still might be a fuel issue , so the next step is to determine what jets are in it and what your elevation is , you should be around what is on the chart below , if not replace the jets to match whats on the list , if the bike was from a higher elevation (or lower) , it will have a issue with fuel delivery

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.

You mentioned a JD Jet Kit , did you buy it or prior owner ?? , was the bike ridden in your elevation ?? , or did it come from a completely different elevation ?? (at least 2000 ft difference) , you need to also check the Needle Clip Position , if its too high (the clip) then the Needle will be too low and may be starving the system , usually the 4th to 5th position is where you want to be , and if its a JD Needle , then you need to determine if its a Cold Weather Needle or a Hot Weather Needle that is in it now , and swap it out for the correct temp needle as they have different tapers for colder or hotter temps (it will be in the instructions for the JD Kit

Check your Fuel Screw adjustment , for the 04 , you should be about 1-1/2 turns out from "gently" seated , then fine tune the adjustment from there , you are going for (when it does finally start , after the choke is closed) the highest idle that turning the fuel screw in/out attains , then set your idle speed from that , not the other way around

I am guessing from your location you should be around 5,000 ft Above Sea Level , so i would make sure you are around a 158-160 Main Jet and a #45 Pilot Jet (if this is your elevation) , 4th on the Needle Clip Position is Stock for your bike , so make sure its at least 4th or 5th from the Top of the Needle (3rd is too high and will make the needle too low) , as i mentioned , this should get you in the ballpark , and can you describe your Starting Procedure ??? , like "4 twists of throttle and full choke and a hard kick" , etc , as this may have a effect on if/when it starts , also you did not mention (since it has a Stroker Kit) if its a Big Bore Stroker or still Standard bore , as this will also make a difference on jetting

If you try to start the bike (using your "normal" starting procedure) , have you immediately pulled the plug (fill the carb bowl , then shut off fuel valve , and pull the tank , then try starting it) right after trying to start it to see if the plug is wet/dry ?? , this will also give a good indication of your starting procedure and if your jetting is off

If none of this helps or it helps but does not solve the issue , then PM leardriver in the Jetting part of this forum , as he is the resident Jetting Expert and he can pinpoint your issues better than i can , but i think this should get you in the ballpark

[Tobbe]

JimDirt

Thanks, for sticking with me here.

As per my location, Bangkok. has an average elevation just shy of 5 feet. So for the sake of argument we can say sea level. It's hot and humid. We are currently around 33 degrees C. and the bike was previously also ridden here.

It only has a stroker with std bore. So no big bore as of yet.
other mods I believe I have described in my tread start.

For the JD kit, it was installed by me.
the jetting when i got the bike was:

Pilot 42
main 170
leak 55
air 100
starter 72

When installing the JD kit I contacted JD and asked for their advise for a good starting point for the jetting. Telling them about my location, climate and all mods.

So it is currently jetted as per their recommendation:
42 Pilot
RED#5 from the top ,
180 main jet

Starter and air jet remains as before. I can't really remember what size Leak jet is in there.

Before the rebuild my starting procedure (if I can call it that since i only rode it like 3-4 times) was, no choke, twist the throttle twice, find TDC, and kick hard. Usually started within three or 4 attempts.
As for now... feels like I tried it all. But I did notice one peculiar thing. If I hold the throttle fully open and try to kick a few times, like 5 or so. then back to no throttle and give it a hard kick. It feels like it's closer to start then before the full throttle, gets another revolution or two of the crank.

If I pull the plug out straight after kicking, it is smelling of fuel and has like a light sheen to it. it's not wet but just barely damp.

For now then I will change my jetting to a 45 Pilot and 170 main (i do not have anything smaller then 170), swap in the original NCYR needle in with clip pos #4 again.
See what happens.

[JimDirt]

Yea , at 91 degrees you should be LEANER not Richer , (refer to what i posted about Jetting Specs and Temperature changes) , if the bike ran before , then it has to be something done by you , so the main discrepancy in the before/after settings is the Jetting being way richer , its weird , when i looked up Bangkok , it said 4.921 ft , for some reason , i interpreted it to be 4,921 (i thought it was a Comma not a Period/Dot , so it is in fact almost 5 ft , not almost 5,000 ft ....my bad

With the temperature , this means you need to be leaner , so hopefully you will get more popping or actual starting by going back to the smaller Main Jet , i do know that i have encountered a similar issue in Washington state , when riding at 500 ft elevation from my usual 2,000-6,000 ft riding range , i ended up going from a 160 (good for my elevation , but would not even run at 500 ft) to 180 main and a 48 pilot (from a 45 pilot) and the Fuel Screw out to 3 turns , from my normal 1-3/4 , so i have seen strange things in jetting , but when asking at the local shops what everyone was running jet wise , that was the recommendation , and the bike ran (did not idle as well as i had hoped , but it did run well)


What i would do is IF it runs or attempts to with the 170 , , then go down in Main Jet size , if it does not fix/solve the starting issue then try the 45 pilot instead of the 42 (you only want to change 1 thing at a time , then test , otherwise you wont know what actually helped or hindered the issue) , this should help with starting and idling , as the pilot might be more of your issue right now

If you PM leardriver , he more than anyone , could give you more complete/correct info about all this , if anyone can decipher a jetting issue , its him

[Tobbe]

So time for an update

I changed the main jet from 180 to 170, got no change.
I changed from the JD red Needle back to stock needle with same clip setting as before i started the tear down. Got no change.

Changed the pilot from 42 to 45, and behold... it didn't start. But I did get a completely different sound from it. So now I am pretty sure that it does fire but can't sustain it.
Will try to go up more in pilot size and see what happens.

To be continued...

[JimDirt]

As mentioned , i ended up having to go to a 48 Pilot at a lower elevation (but i also had to go UP on Main Jet to a 180 , so sometimes what "works" is not always the normal settings , if it does better with the 48 , then try the 180 Main and see if it gets better

Its definitely sounding like a fuel issue though , and you might end up where i did with a 48/180 with 3 turns out on the Fuel Screw , also don't forget to try adjusting the Fuel Screw during these jet changes , so before trying a larger Pilot Jet (remember 1 change at a time , change something , then test/adjust , then change) , try turning the Fuel Screw OUT 1/4 turn at a time (till you get to 3 turns **turn Fuel Screw IN till lightly seated , counting turns till it seats , so you know where you started from , then go out to 1-1/2 as a starting point , then go out and try starting , 1/4 turn at a time , when you get to 3 if the bike tries but still wont stay running , then go up 1 jet size** "pilot") and see if it gets better , this will help determine if you need to go richer or leaner or if its something else

[Tobbe]

Ok, I went up in pilot to 50 and on second kick it fired right up.
The AFR sensor said it was still on the lean side so adjusting the fuel screw out to almost 2.5 turns it sits at a nice 13,5.
Thank you so much for your help. It's highly appreciated.

Now I will change back the main and needle and see if it still runs.
I would prefer to start the tuning on the rich side and go leaner than starting out to lean.

Edit: Switched in the 180 main and JD Red needle.
Still starts and idles fine.

[JimDirt]

According to leardriver: (direct quote from him)

You are looking for a 12.8 or 13-1 A/F ratio. If you are off by one main jet, that equals about .4 A/F, so not enough to notice. These bikes are super forgiving on the main, and you could be off 5 sizes and think that the bike runs good.

and glad its starting now , like i said , when i was in Washington (state , not DC) i had the same issue your having , and ended up going to 48/180 and 3 to 3-1/4 turns out on the fuel screw , which it "should" have been 45/165 1-3/4 , sometimes , ya just gotta be different