What are you doing today? Thread

[barnett468]

Well part of today I spent bolting on more hp to my hole shot king 1981 YZ465, cuz if a lot of hp (by 1980 standards) is good, then more must be even better.

My two main goals with this are, first, to get the first corner even faster than I currently am, and second, to increase the mid range power since it is difficult to increase the low end power. It currently has all the power on the top end that I really need even though these mods should give me even more.

The first mod is to install boyesen fiberglass dual stage reeds in place of the stock steel reeds. I did this on my 1980 YZ250 and it improved the the low end throttle response but I did not do a back to back test, however, I definitely did not notice any significant improvement in power, but these reeds seem to have a noticeable affect on a 465, which is documented by the dyno test results below.

The second mod is to install a 10 mm spacer between the reed cage and cylinder. These spacers have been falsely marketed as "torque" spacers for many years because more often than not, they actually reduce power in the majority of the bikes they are installed in because they increase the crankcase volume. They were originally designed to work specifically with the 1978 YZ400 because that engine had a rear boost port which was around 40% blocked by the reed stop. Installing the spacer on the 78' 400 engine increases the power because the boost port is no longer obstructed.

After checking out my cylinder with the reed cage installed a while back, I noticed that it blocked around the same amount of the boost port that it did on my 78 bike, soooo, my theory is that since it worked on a smaller cube engine with the same problem, it should (hopefully) work on a bigger cube one.

Also, when these particular reeds are installed on the 78 thru 81 big bore yammies, and the factory reed stop is removed as boyesen suggests, around 12 mm of the tip of the center reed will be hanging off into space with no support because of the boost port, and it will quickly break as some 465 guys have determined, lol.

Below is a back to back dyno test on a 1981 YZ465 with the only change between runs being the addition of the boysen fiberglass dual stage reeds. He did not say if he removed the reed cage stop as boyesen suggests, and did not know about the reeds partially blocking the rear boost port, nor was he aware there was a spacer designed to eliminate this problem.




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[El Camexican]

Barns, please print that chart out after you test your bike and draw the “new” power curve on there for us to see the seat of the pants dyno pull. Use a brown Sharpie, cuz you know

[barnett468]

Barns, please print that chart out after you test your bike and draw the “new” power curve on there for us to see the seat of the pants dyno pull. Use a brown Sharpie, cuz you know

No prob, and I have been at this for so long that I am immune to the "placebo" effect, so if it don't do crap, I won't think that it does. I should be testing it this Sunday on the same track I practiced on last week and several other times in the last 2 months, and I am very consistent there and have now memorized all my shift points and "flying" distances etc, so I will easily be able to tell if it does anything. I also need a new back tire, so if this spacer and reed setup helps, then with a new back tire I should easily be unbeatable to the first corner in the vintage class providing I don't wheelie at any point during the drag race to the first turn, and the Perris track is hard to pass on, so even if someone is slightly faster than me on the track (which several people currently are), it will be nearly impossible for them to pass me, but the super experts like Scott Burnwurth and a few others there should still be able to get around me....eventually.

I worked up to being an incredibly good starter when I raced back in the late 70's and was almost always in the top 20% going into the first turn and hole shot more races than I can remember, but after I sold my FMF works bike that they originally sponsored Gary Ogden on until he broke his shoulder, and bought my 78 yz400, I instantly started getting crappy starts, so I called Dave Miller of Miller Mano (now DMC) whom used to partially sponsor me on a CR125, and I told him what was going on. He then told me about the reed spacers and told me to install it and also told me to change my rear sprocket size by 2 teeth, both of which I did at the same time, and at the very next weekly night time pro race at OCIR, I was 3rd (out of around 12) going into and coming out of the first turn, and kept consistently getting good starts again until I broke my friggen leg soon afterwards. The sprocket change certainly helped it get to the first turn faster, but it definitely wasn't the only thing that did because it was a day and night difference in power and acceleration like I was suddenly on a completely different bike.

If this setup gives me even just a small increase in mid range power (like around 3 hp) without loosing any low end (not that it has any to loose now), I will be absolutely ecstatic. If it gives me even more, I will probably need to wear depends when I ride it. The 1 tooth smaller counter shaft sprocket I installed a few weeks ago finally made it barely competitive, and that is just barely in some sections, so it still needs more low end (which ain't gonna happen) or more mid range so I can clear some of these bigger jumps that come immediately after exiting a corner....or I just need to finish putting my 250 back together and start riding that again, but I would still like to remove around 4-5 more lbs from it.

[El Camexican]

I'll be interesting to hear what it feels like. I've never heard of fiber reeds adding top end horse power, but they sure do smooth out "the hit" and on smaller bores they seem to add usable power starting about 500 to 1,000rpm lower than with steel reeds. I've never used a spacer on a bike engine, always thought they were snake oil, but if your cage is against the boost port it might make a big change. I assume the additional width is easily absorbed by the air box boot? How are yours after all these years? My 17 year old boots are already starting to crack.

5 pounds? Aluminum bars, silencer and foot pegs? Tell me your not using the old style foot pegs!

[barnett468]

I'll be interesting to hear what it feels like. I've never heard of fiber reeds adding top end horse power, but they sure do smooth out "the hit" and on smaller bores they seem to add usable power starting about 500 to 1,000rpm lower than with steel reeds. I've never used a spacer on a bike engine, always thought they were snake oil, but if your cage is against the boost port it might make a big change. I assume the additional width is easily absorbed by the air box boot? How are yours after all these years? My 17 year old boots are already starting to crack.

5 pounds? Aluminum bars, silencer and foot pegs? Tell me your not using the old style foot pegs!

As far as ading top end goes, the reeds didn't on my 250, however, as you can see by the dyno chart, they extended the peak rpm by around 500 rpm which is obviously a huge margin but nearly pointless on these bikes because they rev to 7500 rpm anyway which is borderline insane. The reason the guys bike didn't rev to 7500 on the dyno is because he put a torque pipe on it with a ridiculously long head pipe.

My bike basically has no significant "hit" at all. The power delivery is incredibly linear and fairly wide, and I finally have it tuned where I can open the throttle and lug the engine and it carburetes flawlessly and accelerates from nearly idle, however, it just doesn't pull when doing that like a Maico, or virtually any other big bore bike of that era does. The 80 model 465 has a massive jit in the mid range and I have a good 80 cylinder but the 80 pipe is screwed, but those things were borderline dangerous because they came on so hard and I have no interest in taking that type of ride, so I'm going to stick with the slower and smoother 81 setup.

Yeah, the big bore yz's are the only bike I know of that the spacers work on, but as you know, the mfg's will sell anything whether it works on other bikes or not just to make a buck since they already had the pattern for them.

The additional width/length is unfortunately not "easily" absorbed by the boots even though it does not seem like much because the boot on the airbox on these bikes is literally around just 1/2" long, lol, so getting the carb in is very hard, especially with slightly dry 38 year old boots, so one hopes to not have to remove the carb very often. Also, it then locates the carb between the frame tubes enoigh that it can no longer be rotated very far and also makes removing and installing the slide a major pita, but I'm not worried about that because if it works, I won't have to screw with the carb after I rejet it anyway.

I already have a plan to remove around 5 more lbs and I bet you can easily guess what it is knowing me a bit now, but I will give you a hint and say that it has to do with an expensive material. My bars are the original steel ones on my 250 so I will probably get some aluminum ones as well. As far as the footpegs go, yup, I am still using the originals, lol. I have found out that the factory titanium pegs from the newer yamahas will bolt right on and I have seen them for around $40.00 a set on ebay, but unfortunately, the front part of the peg is around 1/2" farther forward which will screw up my shifter and brake pedal distances, so I can't use them.

I was going to modify an aluminum kick starter to fit which will save around .6 lbs but I haven't gotten around to it yet. I would love to get 1o lbs off the 465 but I just don't want yo spend what it will take to do that. I haven't weight both bikes yet but just by pushing them both around, my 250 feels like it is at least 30 lbs lighter which I know it isn't but it literally "feels" like a 125 compared to the 465 now, so when I get back to riding it, it should feel extremely light by comparison because I will also be stronger from trying to hang onto the 465.





arounukintake ned

[barnett468]

ading

should be

adding

PS - If you don't see a test report from me by sunday night, it is reasonable to assume that it worked better than expected and that i am therefore in a local hospital.

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[6bt]

Haven't posted in a while. Some of you wondered how the barn is coming I started in fall of 17'. Had a rough go last year, between the super hot weather, fall rain and losing my dad, not much got done. Wrapped purlins up this spring, and got a deal on a guy to finish the sheet metal. Ordered a roll up door yesterday.

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[El Camexican]

Barn Red sheet, nice. What did you use for trusses?

[barnett468]

That barn looks bigger than your house....hell, it looks bigger than mine too.

[plastikosmd]

Looks great

I think we have the same lift and possibly the same tractor disease. My advise, stay away from dozers! (Heavy, expensive and they multiply like rabbits)

[6bt]

Barn Red sheet, nice. What did you use for trusses?

Just 42' snow rated trusses.

Sent from my moto z4 using Tapatalk

[6bt]

That barn looks bigger than your house....hell, it looks bigger than mine too.

Ah it sure is bigger than the house! My wife is excited 5 bikes can leave the house and migrate into the barn, lol.

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[6bt]

Looks great

I think we have the same lift and possibly the same tractor disease. My advise, stay away from dozers! (Heavy, expensive and they multiply like rabbits)

That's GOHA. A jlg 60 HA lift that was a trade in at my work. A little rough but does the job.

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[barnett468]

After i show an escspe hybrid to a potential buyer this morning i am off to test the new reeds and reed dpacer in the beast. Im taking some silencer packing with me too and will check the condition of the existing packing after a few laps because i never checked it cuz i got lazy and it may very well be blown out and this will affect how it runs as well. If i don't post results tonight you can send me flowers at the perris medical center if you want.

[knappyfeet]

Nice work on the barn...... Can I store some of my stuff in there?... Haha!!!