4 stroke rebuilds

[the_real_wild1]

Just getting back into the dirt bike game. WTF is with all the new four stroke bike ads that say the engine was just done? I expect this to be true of the 2 stokes but not four. Anytime a 4 stroke was rebuilt is was usually due to dropping a valve or water in the engine kind of thing. Have these new bikes become unreliable compared to the older bikes or are people trashing their bikes more? I was looking at a WR or a CRFx. What's the deal???

 

[CamoKVF700]

They usually drop a valve and things get expensive. They also do not like ingesting water. The power curve is awesome for dirt but it costs.

 

[takethebounce]

Modern Japanese MX motors are meant to be ridden hard for 20 mins at a time. They are using components like titanium valves which beat the seats out, require more and more valve adjustment, everything is lighter weight, dual cam, high compression pistons and so on.

Guys who trail ride these things over heat them, sink them in creeks and so on. MX bikes do not make good trail bikes. Sure lots of guys do use them and never have issues but more and more you see the ones that do not work well.

As far as the Honda CRFX, the unicam design is pretty good in those bikes.

 

[4x4racing]

That's why I laugh when they say never raced so u run it through the bush swamp it drop it n mud over heat in slow areas instead of use it for what it was built for and never seen a better maintained bike then a guy that is racing I try to only buy raced bikes with the wr or the x bikes prob not an issue but the 4 stroke mx bikes are strung out race bikes just like the two strokes where just a lot more parts I can remember reading they recommend replacing rings every 11 hours of riding and that is same for two stroke or 4 and having no skirt on the piston makes it lighter but not relible just my opinion I haven't ever lost a valve mostly the front of the cyl gets worn and cause there is no skirt on the piston ..... Or the crappy chain tensioner fails I have found mx bikes show there ware if it looks clean it prob is if it looks beat it prob is

 

[teeroy]

I think the bikes used for racing are usually well worn and need attention, they spend their lives on the track bouncing off the rev limiter for 20 minutes at a time. I heard all kinds of horror stories about how they can self destruct, taking out the whole motor in some cases. bought a 450x new in '06 and plated it, ran it for 5 seasons on and off road before rebuilding the top end. I rarely hit the limiter, I think that has a lot to do with the longevity of the engine. if you rebuild them before they blow it's pretty reasonable, for well under a grand you could do top and bottom end with a new crank and bearings.

 

[Stickyfingers]

4 strokes are definitely not the same as they used to be. They are super high revving torque monsters and most people that buy them do not properly maintain them. I'm my honest opinion a late model 250 2 stroke is just as reliable as newer 450 4 strokes. Some may not agree but if you look at the spread of overall cost between maintenance and repairs 2 stroke wins. I have owned several rm 250s and rmz 450 and yz 250s and yzf 450 that's just how it is. I am finally starting to lean towards 4 strokes only because how easy they are to tune with efi tunes and cdi tunes. Average joe blow who wants a solid budget bike get a 2 stroke!!!

 

[the_real_wild1]

I have been starting to look at the crf450x now as well as the 250x. There seems to be more of them and therefore some good deals out there. Has any one found the 450 and more reliable then the 250? Seems all the 250 have had engine work already.

 

[teeroy]

I have been starting to look at the crf450x now as well as the 250x. There seems to be more of them and therefore some good deals out there. Has any one found the 450 and more reliable then the 250? Seems all the 250 have had engine work already.

the 250's are time bombs, they have to be revving all the time, way less torque and they don't lug worth a chit. go with a 450x for sure, you can tractor them around all day and they don't feel any heavier than the 250.

 

[Bnorth]

I ride two strokes. Most guys I know that race offroad cross country/Hare scramble type events are on two strokes, there's a reason for that. The fast guys are on 300 2t's and run circles aroung the 450 4t guys. It's tough to ride a 450 fast as with so much torque you are always spinning and when you hook up the tire is way in the air. Things are changing with the introduction of the 350 4t's but whenever I see a 450 I tend to assume that it's a staging area or gravel pit warrior not a single track threat.

 

[GYMBRAT]

I was taught at a young age that a race bike is probably the most reliable bike to purchase "usually". They are meticulously maintained and theres a good reason for it. I have purchased both when I was young and had the worst issues with the farm bike with no "hrs". They get rode hard then put away wet "usually".

When I raced, my bikes were in tip top condition 110% of the time. I also love the thumpers BUT damn they are expensive when they break!!!!! I still enjoy my 2 strokes for the reliability and simplicity of them.

JMO

 

[the_real_wild1]

Funny the 350 is mentioned. If I could afford it a 350 would be perfect. The issue is ktm is the only one I have seen and of course it is brand new and out of the budget.

 

[teeroy]

Funny the 350 is mentioned. If I could afford it a 350 would be perfect. The issue is ktm is the only one I have seen and of course it is brand new and out of the budget.

are you planning on racing or entering any woods or hare scrambles? if you are buying a bike to ride around on trails then pay no heed to the advice that you NEED a certain machine because it is the best in racing conditions. if you want reliable and trouble free for cheap then go find an old XR 250....for 90% of the people that want to trail ride it is all they will ever need.

 

[the_real_wild1]

I used to race cross country when I was younger. I started riding when I was 8 on my cousins trikes and bikes. Went from a atc 70, xr 80, ct 70(lol), xr500, kdx220 and finally my last bike was a rmx 250. I am not racing this time around just fast trail riding. But I need the bike to be able to idle along the trails at a slow pace too. All depending on the riders I am with. Because of fawked up joints I really want something with electric start too. That is probably the most important feature.

 

[teeroy]

I used to race cross country when I was younger. I started riding when I was 8 on my cousins trikes and bikes. Went from a atc 70, xr 80, ct 70(lol), xr500, kdx220 and finally my last bike was a rmx 250. I am not racing this time around just fast trail riding. But I need the bike to be able to idle along the trails at a slow pace too. All depending on the riders I am with. Because of fawked up joints I really want something with electric start too. That is probably the most important feature.

XR 500....'nuff said. you must be a rider...lol. what a beast them things were....way too tall, top heavy, and gobs of torque. but you could fly thru the junk like nothing else out there lol.

I was pretty unsure about buying the 450x after coming off a KX 500, after the first few rides it didn't take long to realize I had not made a mistake. I would still love to have an old 500 smoker just to abuse, I just don't have it in me to throw the 450 away on a bad climb like I used to with the KX. I never liked the 250 smokers, they were too light and snaky for the style of riding I liked. smaller guys seemed to do well on them, the 450x to me seems to be a cross between a 250 and 500. I loved the torque of the 500 and being able to short shift when I wanted, the 450x is a lot like that but seems a lot more stable than a 250. the e-start button is a godsend, I love it.

 

[the_real_wild1]

I fricken loved that 500 except for starting the odd time. I raced a cbr600 once, while in a smooth ditch. He tried to lose me and it took awhile to do it. Of course once he got into about 3rd or 4th he was gone. 160 km/h top speed. I was thinking the 450x should have the wider gear ratio over the r so it should be good in the woods to putz along. I wish I could put some time on both the 250 and 450 and then decide.

 

[teeroy]

I fricken loved that 500 except for starting the odd time. I raced a cbr600 once, while in a smooth ditch. He tried to lose me and it took awhile to do it. Of course once he got into about 3rd or 4th he was gone. 160 km/h top speed. I was thinking the 450x should have the wider gear ratio over the r so it should be good in the woods to putz along. I wish I could put some time on both the 250 and 450 and then decide.

I ride with more than a few 250X models, they just seem like they are way low on jam. there are a few things about the X models that are different from the R's, different frame, steel valves, wider ratio box, lower rev limiter (9600 compared to 11,600). for sure you will have to try them both to compare, if you rode an XR 500 you will be disappointed with the performance of a 250.

 

[the_real_wild1]

I tried out a buddies yzf450 last year. It was ok for power. The issue I found was I was always looking for the next gear. It was one of the 4 speeds though and it was gears pretty high for riding in the woods.

 

[takethebounce]

The 350 is only about 7-8 hp less than the 450 now. And at the same weight aside from cost it is not overly noticed that it is a 350. The power is a bit smoother on the bottom end. I spent some time on one. Nice bike but for me, still heavier than my 2 stroke.

I do not know if I would ever go back to a 4. A ktm 250 xc or xcw ( 2 strokes)
I think has enough jam for most guys. I run a 200 but I am not a big guy either. The 200 shines in tight stuff as well.

The nice thing with bikes is no matter what you can almost find parts for them relatively cheap in comparison to sleds. A full set of plastics can be found for $100. Awesome way to improve a bikes looks. Rubber is cheap, chains and sprockets cheap, especially on 2 strokes. 4 strokes wear out chains a little quicker.

Ahhh hopefully on a bike in another month.


sent from a top secret location

 

[the_real_wild1]

Not sure if I want to do another 2 stroke. I have been starting to look at them though. Price would have to be right as well as the bike. It has to be a wide ratio trans and big tank etc. KDX, RMX kinda thing.

 

[goodngrubby]

I have a CRF450X, CRF250R, and an older (2000) WR400. Come on down and spend a bit of time on all 3 of them....I'll make you a smokin deal on whichever you like the best.