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Need some help making my bike a better trail bike.

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So I was set on selling my 2005 YZ250 2 stroke and buying something like a CRFX or WR but living in kodiak bikes are expensive and hard to come by. There is a track here but dirt here is mostly rock. FYI thats why people call kodiak the rock. Also I am slow on the track and a tend to crash when i give it a lot of go juice. So trail riding is what i really like. My bike is for the most part stock. I need help on setting my suspension correctly ( I am 6'1" 230lbs) and jetting it correctly. Altitude here is from sea level to around 1500 feet on the trails. Fuel ratio and what type of tire can take a hard rock surface. Its a lot for one thread I know.

Bought the bike last year and some issues I had last year trail riding is I fouled NGK B8ES plugs every day I rode. I checked the jetting and it is still stock. Fuel ratio I went from 32:1 fouling a plug every ride to 40:1 now just fouling a plug each day i ride. Also how to keep water out of my air box. It rains a lot here and there is a lot of stream crossings. The filter doesnt get soaked but it can become a little moist. That cant be the only reason im fouling plugs cause on dry days with now water crossing i still fouled plugs. Now to setting my suspension. The terrain here beats the heck out of me. I know i cant get a smooth ride but there has to be some little things i can do to make it a little softer. Just trying to get ready for summer, i cant ride now due to 5ft of snow on the ground but some advice is always good.

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Good day TGardner.

You might find this generic YZ250 jetting table handy for starters.... Cheers!

yz250vjettingxg4.jpg

Find it strange however that you always foul plugs.... If you're on stock-jetting and if your float bowl is at stock height/depth, might i suggest start experimenting on leaning out your jets. Just use jets like the Keihin before thinking about the JD jet kit. The table above is not 100% applicable to all people, and you have to re-jet determininistically until you find the right combo. Also, like RCannon suggested to me in the past, tinker 1 type of jet at a time, and go down 1-step at a time. Ride the bike quite long enough, say a day's trail and check. Stick only to one type of fuel and premix ratio.

Where i live, the temperature here varies only between hot and very hot all-year round, i.e. between 25ºC to 40ºC (about 80ºF to 100ºF) and it's humid. Our trail sites can be around 550 metres above sea level (1800 ft) and i am jetted at 45 pilot and 172 main jets, N3EW needle is in stock position, same plug temp as yours NGK BR8ES, stock engine and stock pipe on. Premix at 32 : 1 with 100-octane RON gasoline and Motul 800 offroad-line 2T.

I am confident to say that i have never fouled any plugs, whether i ride fast in wide-open backroads or just putt-putt in tight trails with matching paddling of my feet :lol:. Although my jetting is not 100% spot-on based on the looks of my plug, my plug is nonetheless dry and brown, and my pipe doesn't drool....

dsc01050.jpg

noelXR200.jpg

Given time and a li'l bit of work you will find the right jetting combo for you man.... GOODLUCK! :bonk:

Edited by joshua_inigo
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Get that suspension dialed. You are heavier than it was planned for and riding slower than it was planned for encountering sharper edged hits....than it was planned for.....start here. If you are fouling plugs, you have issues. You are lucky in that you get to ride low alt with cool air, a recipie for power. I would spend the money to get the squish corrected, that will help. Read up on timing. you can really help tame the beast there.

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You are not fouling the plug from having too much oil. I run 32:1 and NEVER foul a plug. I haven't fouled a plug since I had an ancient Blazer that burned oil like the Dickens.

Your bike is too rich. You need leaner jetting. Probably the pilot jet in particular is what is fouling your plugs.

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CaveMike feel best way become fast in woods is live in woods. CaveMike live under log in woods and him very fast.

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ingo

Ok thanks I looked everywhere for that jetting table last night. I new it was out there. The temps here are in the 50-60s F throughout riding season. Cant remember but is it the lower the number jet the more lean or other way around. According to the table i can leave the needle clip where it is in #2 position. ( Thank goodness I hate adjusting those) and maybe go up on main jet to 180. I dont know if i should even mess with the main jet. I have a 50 pilot do i want to go down or up. The table says around a 51-50 for my temps and alttitude. I know the table is just a quick reference and not specific to my bike.

Greg

Explain to me about the timing. What is it and where can i find info on it. Spend the money on getting the squish corrected. What do you mean take it to a mechanic or buy aftermarket shock. Sorry I am having a hard time understanding what your saying. Thanks

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I took away some snap from my YZ250 and emphasized torque with a Rekluse Pro.

That jetting chart will work.

If you hafta send out the suspension there's plenty to chose from. You can get gun cases at Wal Mart to ship yer stuff. I had mine done at LT Racing in Port Orchard WA. Made a good difference regarding control. Far far less crashing. I do not ride tracks.

Also, Does CaveMike have good raingear? Coz Kodiak gets some rain which tends to slow you down some when yer wet all day.

Tape up air box inlet behind mud flap near shock. That will help much on stream crossings.

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The timing on the yz is adjustable. A very little bit makes a big difference. If you search for yz timing thread, it should give some good pics. Mark where it is now with a scribe or knife so you have a reference mark. It takes a dial indicator to measure exactly where it is, bit if you know where you are now, you can back off and if you don't like it....easy to

Squish is the space between the piston and dome at top dead center. It should be in the .050" neck of the woods...but I bet it measures .072-.077" it makes a difference. I am pretty sure I still have pics in my build thread of me cutting my domes....might shed some light.

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I would say your plug fouling is due to a mechanical issue such as a worn top end, worn cranks seals or bad reeds... you shouldn't foul with the stock jetting at those temps and alts.

I generally run a BR7ES plug for trail riding due to the slow speed work.

A trials tyre sounds like it would be great for where you ride..

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I would say your plug fouling is due to a mechanical issue such as a worn top end, worn cranks seals or bad reeds... you shouldn't foul with the stock jetting at those temps and alts.

I generally run a BR7ES plug for trail riding due to the slow speed work.

A trials tyre sounds like it would be great for where you ride..

I forgot to add that i had the top end and bottom end rebuilt last august by a bud who rebuilds ATVs and bikes on the side. I ran it a handful of times after the rebuild and it ran good but still fouled the plug every day i rode. I did a little research last night and i might try a synthetic oil at 50:1 with a pilot jet adjustment. When i removed the engine for the rebuild i pulled the reeds out and inspected them. I thought they looked fine no cracking or chipping and seemed to work properly. I am almost sure though there still stock. Do they wear out?

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The timing on the yz is adjustable. A very little bit makes a big difference. If you search for yz timing thread, it should give some good pics. Mark where it is now with a scribe or knife so you have a reference mark. It takes a dial indicator to measure exactly where it is, bit if you know where you are now, you can back off and if you don't like it....easy to

Squish is the space between the piston and dome at top dead center. It should be in the .050" neck of the woods...but I bet it measures .072-.077" it makes a difference. I am pretty sure I still have pics in my build thread of me cutting my domes....might shed some light.

I will get to that some time this week. Will that have an effect on the plug fouling. How do you adjust it? Lets say that is good, the highest octane here at the pump is 90 octane. We have 100LL but that is about $8 a gallon. Maybe add some low lead to the fuel.

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When i removed the engine for the rebuild i pulled the reeds out and inspected them. I thought they looked fine no cracking or chipping and seemed to work properly. I am almost sure though there still stock. Do they wear out?

Yes, reeds wear out. Check for chipping or a gap large enough to pass light through the sealing edges.

I will get to that some time this week. Will that have an effect on the plug fouling. How do you adjust it? Lets say that is good, the highest octane here at the pump is 90 octane. We have 100LL but that is about $8 a gallon. Maybe add some low lead to the fuel.

Buy the 100LL gas and mix it 50/50 with pump.

Edited by shrubitup

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ingo

Ok thanks I looked everywhere for that jetting table last night. I new it was out there. The temps here are in the 50-60s F throughout riding season. Cant remember but is it the lower the number jet the more lean or other way around. According to the table i can leave the needle clip where it is in #2 position. ( Thank goodness I hate adjusting those) and maybe go up on main jet to 180. I dont know if i should even mess with the main jet. I have a 50 pilot do i want to go down or up. The table says around a 51-50 for my temps and alttitude. I know the table is just a quick reference and not specific to my bike.

Tgardner77,

I'd like to reiterate and impress upon you what the gentlemen Shagger, Shrubitup, and Vintage_Not_Pimpage advised you to check.

You are not fouling the plug from having too much oil. I run 32:1 and NEVER foul a plug.

You will NOT foul a plug from running more 2T oil, believe it or not, that's why i'm running 32 : 1 and yes it's the thick Motul 800 2T offroad i'm using.

Yes, reeds wear out. Check for chipping or a gap large enough to pass light through the sealing edges.

Plus, check your reeds and seals.... I had a 1st-hand experience on unseated reed petals myself from my former YZ125 with a VForce 3. No matter what jetting adjustments i did, my plug was always wet and sooty. And then someone advised me to check the reeds, and alas my petals are no longer seated well.

Kind regards.

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Ok tomorow i will pull the carb and the reeds for inspection. I read about timing the bike and am still a little fuzzy on it but will see what i can come up with.

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Also, Does CaveMike have good raingear?

CaveMike have many different types animal skins for him wear in bad weather. Him have some modern human clothes him find on dead hiker. CaveMike eat dead hiker, but keep pants.

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The best set up for a YZ for trails that I have found is a steahly fly wheel weight, one tooth smaller on the front sprocket and then a FMF Gnarly pipe. that gives you a little more of a mellow hit on bottom so you can crawl over wet rocks and roots. I also use race gas. can't trust what comes out of the pump. plus ethenol is not good for small engines. I use Klotz 112 mixed 50/50 with 91 pump. that stopped my plug issues. Also remember you are riding a pinger, they liked to be ridin hard. get on the pipe and you will be all smiles.

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