1999 YZ400 – first riding impressions

Well, I've spent 2 days riding the YZ now and I'm...stumped. It doesn't do anything badly, I'm just a little underwhelmed.

In fairness; I ride mainly on gravel roads and off road tracks. Flat out stuff with a turn here and there, no jumps or anything of that sort. Most probably I'm being unfair to this bike by rating how it performs on tracks like that but I reckoned if it could handle full on motor cross, this should be easy. I've ridden a few bikes before, the last being a 1981 Honda XR500. That bike, with the exception of its brakes, was absolutely perfect for my purposes. I flipped it doing a wheelie and sold it, a decision I now regret. If I had the choice, I would rather be riding that bike than the YZ.

You ask why, here are a few reasons:

• The technique to kick start the YZ differs from day to day. Yesterday I had to pull the choke out, open the throttle just a little bit and kick it. That worked great for the whole day, regardless of whether the bike was hot or cold. Today, no choke. If you touch the choke, it doesn't want to start. So today, it started no problem all day with the choke in. Before I came to the farm (where I'm riding now), you just HAD to use the hot choke to start it when it was warm. Tomorrow will probably require a new technique...
  

  The XR was pretty simple in comparison – push the kick start till it locks, decompression in, push kick start from top to bottom, decompression out, kick, it starts.
  

• This bike is heavy. It's supposed to be 20 kg or so lighter than the XR was. To me, it feels the same. It didn't bother me on the XR and in honesty, doesn't bother me that much on this bike. But, geez, the XR is known as a heavy bike and this is supposed to be a motor cross machine. I can also tell you that this bike is WAY, WAY heavier than the KX125 I used to ride.
  
• This bike, I swear, makes less or the same power as the XR. Again, I must mention that the gearing on the XR had been dropped to 110 km/h or so flat out by fitting a larger sprocket, but still this doesn't make sense. This part puzzles me the most and I'm still not sure what to make of it. Read reviews on the YZ and most of them mention mad power with wheelies in any gear etc. etc. Well, it does accelerate strongly but I'm not shitting myself or anything like that. I can't decide if it's because I'm just getting too much wheel spin or if the bike is just not that strong. Having said that, I took it out on tar a few weeks ago and it seemed crazy fast, it must be the wheel spin issue then. Weird... The XR must have hooked up a LOT better then.
  
• The bike isn't very stable, I'm getting "headshakes" accelerating, and sometimes just riding normally. I'm not getting this behaviour consistently though, it's like the lotto. When you least expect it, there she goes! This is very disconcerting, is this even normal?
  
• The engine on this bike gets extremely hot, and I'm not doing slow riding so the engine is definitely getting enough airflow. I've checked and all the fluids etc. are fine. If the engine was crazy powerful, I would understand. But comparing it to the XR, it is water cooled and has 2 radiators in its favour. Surely it should be running cooler.
  

My logic is telling me that I've just forgotten what the XR was like to ride. Probably if I ride it and the YZ together now, the XR will feel ancient. Maybe my expectations were too high. This bike is just not giving me a buzz...at all.

I'm either going to take it in for some tuning to see if that makes a difference, or I'm going to sell it. At this stage, I'm leaning towards selling and buying a 250 2 stroke.

Yamaha workshop manuals

If you own an older bike, you're probably going to invest in a manual at some stage. If you're riding a Yamaha, have a look at the Yamaha Europe website. You might just find a manual here, and save yourself some money.

You can search for manuals here:

http://ymenvom.nl/search.php

If you ride a YZ400 or WR400, look here. The manual is for a WR but is 99% accurate for a YZ too. 654 pages, bargain!

http://ymenvom.nl/manuals/M5GS-30.PDF

1999 Yamaha YZ400 – rough idling

If you own a 1998/1999 Yamaha YZ400, you're probably going to know that these bikes are extremely finicky. If the planets aren't in alignment (exactly) and the wind isn't blowing in the right direction, and it isn't the right time of the month, all that kick start is going to give you is...nothing.

I'm exaggerating, but really they are finicky. If you read the previous blog, you'll know I got the bike to start but it was idling rough and was backfiring. Having read a few articles, I figured it must be the pilot jet, which I had screwed completely shut. So...the recommendation is ½ turn out minimum for a lean mixture, 2 turns out maximum for a rich mixture. I had it at 0 turns out so obviously the bike was leaning out, which the rough running and backfiring seemed to confirm.

I want to ride this bike in 2 weeks on my parents in law's farm, so I had to get the idling and running sorted, which I figured would be pretty easy. I had read that a rich mixture resulted in degraded performance and according to me this was fine, I wanted the bike to idle and run smoothly. If performance suffered a bit, I didn't care; the bike has more power than I can handle anyway. I was going to turn the pilot screw out 2 turns; the bike would start and run fine, little less power, no problem.

Ok, that was the theory. First issue is that the pilot screw is hidden in an inaccessible hole right under the carb. You can either buy a special Yamaha tool, which I was not planning to do, or make another plan. After a bit of experimentation, it turns out you can unclip the pipe between the carb and engine, and then pull the carb towards you enough to get a short screwdriver into the pilot screw hole. I did that, turned the screw all the way in and then turned it 2 turns out again. I put everything back again and tried to kick start the bike. Nothing, absolutely friggin nothing. Usually you can hear if the engine wants to start, in this case it was stone cold dead. Right, so I tried all the options for trying to start a YZ400 (previous blog). Nothing, absolutely nothing...

Ok, my logic says that if the engine started with the screw turned fully in, and if the normal range for that screw is ½ turn out to 2 turns out, then logically it should at least start at ½ turn out. So I repeat the whole procedure and set the screw to ½ turn out. Try the kick start thing again...absolutely dead...nothing...

Now this is a problem, I can't really turn the screw back in much more, we're heading back to no turns in again and that's where the bike was idling rough, so what now? Remembering that setting the idling speed helped last time around, I turned the idling screw out 10 turns or so. I did my usual "compression lever in, 10 kicks to clear everything, compression lever out, kick and see if it will start" routine a few times and the bike was still dead. So I started turning the idling out 1 turn, kick start routine, 1 more turn out etc. until I could hear the engine showing signs of life. Another 3 turns out doing the kick start routine every time and the bike started, idling smoothly. I let it idle on choke for a while and then switched the choke off. The bike was still idling smoothly, success!

Right, now for a quick drive around the block. Before I say anything further, I must mention that I have owned and ridden the following: a 1981 Honda XR500, a 1989 Kawasaki KX125 and a 2005 Suzuki LTR250 quad. The first thing I noticed was that the brakes on this was 10 times better than anything I'd ever ridden before. Then I noticed the performance...the previous owner had told me that the bike wheelies in third if you open up the throttle so I decided not to go there yet. I snicked the bike into fourth, lowish revs and opened the throttle ¾ or so. Holy crap, I shit you not, this bike will out accelerate anything I've ever ridden before easily. EASILY...! None of my previous bikes would match this performance in second, at full throttle, at full revs. If this is what a 10 year old bike feels like, I can imagine riding a modern motocross bike must be absolute madness!

Anyways, I'm set for the farm and will have nearly 3 weeks to get to know this bike better. When I'm back, I'll post my "findings". J