i recently rebuilt the top end,it started and ideled fine but it was hard to start. today i set the flotes and it started right away but i could not control the idle and also noticed the base gasket was wet its only been started 3 times since rebiltwill this cause the problem? also the base gasket covered 2 transfer holes at the back of the block,should i trim them out? its a wiseco gasket kit. thanx guys!
High idle on cr480
- Thread starter 480 mike
- Start date
2 strokes for life
Member
- Jan 3, 2007
- 1,860
- 0
480 mike, try and trim them out and use anorobic sealer to get a good seal. Also, if you adjusted the float to the correct setting that could mean the bike had been jetted befor with the wrong float setting. Witch would also cause this high idle of yours.
Have you seen the price of anerobic sealer? Yeesh. Anyways, those transfer ports certainly shouldn't be covered but that doesn't explain why the gasket is leaking. If you pull the cylinder, you may see where it is leaking from by a trail of oil. I would take a straight edge to the cases and bottom of the cylinder to ensure they're flat. Save some money and use any sealant but the anerobic stuff. I tned to shy away from silicone due to its tendancy to plug coolant passeges and such. If everything is smooth and clean, Ideally you don't need a sealant on that gasket.
2 strokes for life
Member
- Jan 3, 2007
- 1,860
- 0
76GMC1500, well up here in Canada it dose not cost too much. I use it on everything. Must suck having a bad price on it.
- Thread starter
- #5
i found out what the problem was...some retard tryed to split the jug with a screwdriver and dented the jug a bit so i put gasket sealer and a new gasket and is hoping for the best. before i put it on dry not knowing about the dent...is very small but thats where it leaked from,i fixed it today so WEEEEL see what happens thanks for the info guys i will keep you posted c-ya.
Check your choke valve for wear. If that is okay then check the plug.
2 strokes for life
Member
- Jan 3, 2007
- 1,860
- 0
480 mike, it was called an ankel breaker for a reason. But it might also have lean jetting off the bottom witch would make it hard to start.
Last edited:
Plated or sleeved? New.honed or worn?
I would hot,cold cycle it,a couple of times,then ride it easy a couple times then let her rip! Fresh iron liner and rings need a little bit to seat.
- Thread starter
- #14
im goinging to midland airport(which is about 40 min from me) they still sell av100 low lead instad of no lead to the public.its about 7 a gallon but its good buring purple fuel.im taken the old beeeach up to the cottage this weekend and break her in for all shes worth. this bike was a complete resto incl power coated frame,pictures to come soon,thanks for the info.mike
Uh oh! You did not do a search on that subject! http://www.dirtrider.net/forums3/showthread.php?t=113140&highlight=avgas, I would recommend checking this out instead,the Firepower 537 and Xamax oil, Xamax transmission oil,and Race Kool are unprecedented! http://www.precisionautoresearch.com/page4.html
- Thread starter
- #16
thanks for the info but i used this fuel in snowmobiles and super comp cars that i race and they never lacked throttle responce and inproved the 60ft time and top end in the race car.510ci 13;1 850 hp straght motor without NOS in a 68 cheyll nova also the snowmobile was a 500cc free air and ran on that since new..never blew a piston or flowed a plug it could idel for hours and never foul a plug or stall but there is some small jetting to do if you want to run it straight,also it always mixed with oil fine.
Well,how about this one,http://dirtrider.net/forums3/showthread.php?t=150687&highlight=avgas
- Thread starter
- #18
a 5 gallon gug of vp c-12 is 90 bucks apposed to the av. ran it today and ran fine no jetting required on the big bore,and was more responsive 5 gallons of av 100ll was 40$.i read the other day to lean the bike over from side to side then put it in 1st and pull it back and forth a few times because its a beech to start first i tried it my way and buddys worked perfect. jeeeez thats a weird way to start a bike but if it saves my leg thats good with me.
- Thread starter
- #19
the only thing with this bike is the compression seems low. it has a new top end and new reeds,the only thing that was not changed were the crank seals so i took the mag cover off looking for oil and or play in the mag....nothing. any ideas? mike.
zoommx
~SPONSOR~
- Apr 23, 2001
- 282
- 0
Bad crank seals won't cause a noticible compression problem. Did you check the ring end gap in the fresh bore before assembling? Should be less than .020" I would think. Probably about .010" would be best. Let us know if you find out why the compression is low. The leaky base would've been the idling problem due to it sucking air in.
Measure it. If the compression is low you have a head leak or bad rings. Leak down test could show a leak in the bottom end,nothing to do with your compression. I would think if you ran straight mtbe it would be hard to start with issues! Firepower 537 is about 65 for 5 gallons. the boost is 20,the transfluid is 20,Race Kool 20 and the 2 cycle oil is 20! Unmatched throttle response,consistent product for jetting and it smells awesome! Who ever sold you the piston and ring should have the ring end gap and skirt to wall specs. If the seals are bad it will not run well,or start well.
- Thread starter
- #22
im not getting this ,i started it today leaning it over and it fired up. i let it warm up then put my skid lid on while it ideled for 2 minutes the thing went streight up in 3rd like a joke when i check the compression its always cold mabe i should check it when its hot and see the diference thers no sign of head gasket keak its all dry. its hard to belive its 75psi cold i used a snap-on serew in guage and re checked it with a ****ter they were out about half a pound whats up?..the rings were checked when the piston was fit. appricate the info,mike.
The 250 has a shorter stroke,they have kicked me worse also. The 500 is all technique,and a properly jetted bike. The leaning over is for fresh gas or your float valve,if you have not replaced it,do so. How does it run on straight premium gas? And Rich has tried to explain the av gas,so many times!
Technical archives,by Rich Rohrich: "There are at least 100 different threads on race fuel & AvGas that will explain all this in excrutiating detail.
Here's just one of mine that I found.
The simple answer is:
100LL (Blue) Avgas seems to be the most readily available version so I'm assuming that's what we are talking about. 100LL Avgas USUALLY isn’t the best choice but it won't hurt anything.
** For those of you in a hurry, or just sick of me rambling on about this crap skip down to the bottom of the thread to the >>>>>> for a summation.
For those of you still with me, here are some details.
Contrary to popular belief this isn't 100-octane fuel. Aviation fuels are rated on an ASTM Lean/Rich performance number system. 100LL is rated at 91/96 By comparison; Unocal Leaded race gas that is used in lots of spec fuel racing classes has performance number of 112/160. 100LL is closer to 91 octane (MON); by comparison VP C12 is rated at 108 (MON).
For our purposes Avgas has a couple of problems:
1) The 90% boiling point for 100LL Blue Avgas is set at 275 degrees F, which in an engine that turns over 7000 rpm will likely make less power than a fuel that has it's 90% point lower. Pump gas has similar problems, but most good race gas will have 90% Point MUCH lower. As an example Phillips B32 has a 90% boiling point around 235 degrees F and VP C12 has a 90% boiling point around 220 degrees F.
2) Depending on the refiner 100LL can have fairly high aromatic hydrocarbon content, in the 30% by weight range. This level of aromatics will tend to make the throttle response mushy and flat in applications that see big throttle opening transitions on a regular basis. It's similar to what happens when you dump a lot of Toluene based octane booster in your fuel. Throttle response becomes a distant memory.
3) The vapor pressure and distillation curve of Avgas just doesn't seem right for our purposes. The distillation curve or Volatility curve of a fuel determines to a large degree the warm-up, transitional (on & off) throttle response, and acceleration characteristics of an engine.
Here's the simplified version:
A fuels distillation curve designates the maximum temperatures at which various points between 10% and 90% of the fuel will be evaporated as well as the maximum end point temperature. So for any Engine/Air Temperature combination there is a minimum volatility that is required for proper running. As you probably know gasoline is made up of different hydrocarbons, with different boiling points. By combining these
Hydrocarbons together you get a Distillation/Volatility curve. Some hydrocarbons (light ends) boil off at low temps some at much higher temps. Depending on the intended application, a petrochemist will blend hydrocarbons to get a curve that matches the rpm range, temp, altitude, and acceleration characteristics for the application. The problem with avgas as a race fuel is the fact it is blended for an application where
Acceleration and throttle response is not a high priority. If you think about the average light airplane application, you're talking about a fairly low compression engine that runs in a fairly narrow rpm band, and is rarely called on to provide the type of transitional throttle response that a high rpm, acceleration critical application like motocross does. What's more important to the Avgas designer is controlling mixture strength by eliminating the possibility of vapor lock and icing while making sure that light end hydrocarbon fractions don't boil off too early. The lowered rpm ranges used in these engines allow them to push the boiling point up on the upper end as well. As you can see, by using straight Avgas or by mixing various types of fuel together you are modifying a number of important fuel design parameters. You may hit on a combination that works well, but more likely you'll have an engine that doesn't detonate, but doesn't accelerate very well either. So Avgas is SAFE, but not a very good choice. The high paraffinic hydrocarbon content of 100LL makes a very good base stock if you want to play back yard petrochemist, and I believe this is how some of the smaller race fuel blenders start out. I can tell you from experience that it's a ***** to document and test various changes unless you have a lot of time and patience, so trying to come up with your own Super Fuel is probably more trouble than it is worth.
So it sounds like Avgas is really bad for our purposes, and for the most part it is, but given the sorry state of pump fuel today, Avgas is looking better all the time.
>>>>>>
Here's my short course take on things based on my experience and personal biases, (keep in mind this is pretty generalized)
- In almost every case 100ll Avgas is a better choice than alcohol pump fuels
- If you don't need the additional octane that 100LL provides, then MTBE based pump premium (especially Amoco) will tend to provide better throttle than Avgas assuming you have any jetting skill. If you can't jet you're just wasting your time worrying about any of this stuff on a stock bike.
- Mixing 100LL Avgas with a good race gas designed for your application and rpm range is a reasonable way to save some money.
- Mixing alcohol based pump fuels with ANYTHING in an attempt to make it BETTER is just a chemical circle jerk, and if you're that cheap or that ignorant you deserve the crummy performance and the insurmountable jetting problems that you will invariably be blessed with.
- Milspec Avgas is a different animal entirely, but isn't readily available so we won't worry about it.
- The correct race fuel for your application will outperform ANY of the above, regardless of whether the engine is stock or modified. The more demon tweaks hiding in your engine, the more you have to gain." It will start a lot easier with the proper,or better fuel!
Technical archives,by Rich Rohrich: "There are at least 100 different threads on race fuel & AvGas that will explain all this in excrutiating detail.
Here's just one of mine that I found.
The simple answer is:
100LL (Blue) Avgas seems to be the most readily available version so I'm assuming that's what we are talking about. 100LL Avgas USUALLY isn’t the best choice but it won't hurt anything.
** For those of you in a hurry, or just sick of me rambling on about this crap skip down to the bottom of the thread to the >>>>>> for a summation.
For those of you still with me, here are some details.
Contrary to popular belief this isn't 100-octane fuel. Aviation fuels are rated on an ASTM Lean/Rich performance number system. 100LL is rated at 91/96 By comparison; Unocal Leaded race gas that is used in lots of spec fuel racing classes has performance number of 112/160. 100LL is closer to 91 octane (MON); by comparison VP C12 is rated at 108 (MON).
For our purposes Avgas has a couple of problems:
1) The 90% boiling point for 100LL Blue Avgas is set at 275 degrees F, which in an engine that turns over 7000 rpm will likely make less power than a fuel that has it's 90% point lower. Pump gas has similar problems, but most good race gas will have 90% Point MUCH lower. As an example Phillips B32 has a 90% boiling point around 235 degrees F and VP C12 has a 90% boiling point around 220 degrees F.
2) Depending on the refiner 100LL can have fairly high aromatic hydrocarbon content, in the 30% by weight range. This level of aromatics will tend to make the throttle response mushy and flat in applications that see big throttle opening transitions on a regular basis. It's similar to what happens when you dump a lot of Toluene based octane booster in your fuel. Throttle response becomes a distant memory.
3) The vapor pressure and distillation curve of Avgas just doesn't seem right for our purposes. The distillation curve or Volatility curve of a fuel determines to a large degree the warm-up, transitional (on & off) throttle response, and acceleration characteristics of an engine.
Here's the simplified version:
A fuels distillation curve designates the maximum temperatures at which various points between 10% and 90% of the fuel will be evaporated as well as the maximum end point temperature. So for any Engine/Air Temperature combination there is a minimum volatility that is required for proper running. As you probably know gasoline is made up of different hydrocarbons, with different boiling points. By combining these
Hydrocarbons together you get a Distillation/Volatility curve. Some hydrocarbons (light ends) boil off at low temps some at much higher temps. Depending on the intended application, a petrochemist will blend hydrocarbons to get a curve that matches the rpm range, temp, altitude, and acceleration characteristics for the application. The problem with avgas as a race fuel is the fact it is blended for an application where
Acceleration and throttle response is not a high priority. If you think about the average light airplane application, you're talking about a fairly low compression engine that runs in a fairly narrow rpm band, and is rarely called on to provide the type of transitional throttle response that a high rpm, acceleration critical application like motocross does. What's more important to the Avgas designer is controlling mixture strength by eliminating the possibility of vapor lock and icing while making sure that light end hydrocarbon fractions don't boil off too early. The lowered rpm ranges used in these engines allow them to push the boiling point up on the upper end as well. As you can see, by using straight Avgas or by mixing various types of fuel together you are modifying a number of important fuel design parameters. You may hit on a combination that works well, but more likely you'll have an engine that doesn't detonate, but doesn't accelerate very well either. So Avgas is SAFE, but not a very good choice. The high paraffinic hydrocarbon content of 100LL makes a very good base stock if you want to play back yard petrochemist, and I believe this is how some of the smaller race fuel blenders start out. I can tell you from experience that it's a ***** to document and test various changes unless you have a lot of time and patience, so trying to come up with your own Super Fuel is probably more trouble than it is worth.
So it sounds like Avgas is really bad for our purposes, and for the most part it is, but given the sorry state of pump fuel today, Avgas is looking better all the time.
>>>>>>
Here's my short course take on things based on my experience and personal biases, (keep in mind this is pretty generalized)
- In almost every case 100ll Avgas is a better choice than alcohol pump fuels
- If you don't need the additional octane that 100LL provides, then MTBE based pump premium (especially Amoco) will tend to provide better throttle than Avgas assuming you have any jetting skill. If you can't jet you're just wasting your time worrying about any of this stuff on a stock bike.
- Mixing 100LL Avgas with a good race gas designed for your application and rpm range is a reasonable way to save some money.
- Mixing alcohol based pump fuels with ANYTHING in an attempt to make it BETTER is just a chemical circle jerk, and if you're that cheap or that ignorant you deserve the crummy performance and the insurmountable jetting problems that you will invariably be blessed with.
- Milspec Avgas is a different animal entirely, but isn't readily available so we won't worry about it.
- The correct race fuel for your application will outperform ANY of the above, regardless of whether the engine is stock or modified. The more demon tweaks hiding in your engine, the more you have to gain." It will start a lot easier with the proper,or better fuel!
- Thread starter
- #25
took it up to the cottage to break it in last weekend.she ran top noch other than a small crack in the pipe at the top buy my knee lots of power and good top end.the sand pit looked like a grader went through it after i was done.only mixed super with some octaine boost and seemed to like it also had to tighen some bolts(i guess i missed them with the locktite,so for so good thanks for all the help another one lives! mike.
