Repsol 301RR hot start issues + Avgas discussion

[lemur]

8 hours ago, leosantanalg said:

The little decompressor you talking about has an adjustment or runs off the exhaust valve adjustment? 

The decompressor is a little tiny (spring loaded) weight that is built right onto the camshaft.  The valve clearance is the only adjustment.  It's a one shot decompressor, if it don't work on the first rotation it won't work.  It's on there so that the engine can complete 2 rotations of the crankshaft and start the fuel pump pumping.  All you are really doing to start the 4RT engine is to spin it up to idle speed, you don't want to jab at the kick starter like a 2-stroke.

Once running the engine will lug down well below the idle start speed before it goes Ker-Puck! and flames out.

100LL avgas contains Tetraethyl Lead ☠️ 

... curious why the 2022 models would have fuel pump problems after they have gone so many years without significant changes.

Absolute best way to trouble-shoot a 4RT problem is to own 2 of them and swap assemblies until you find something that fails.  

Edited August 11, 2023 by lemur

[leosantanalg]

9 hours ago, lineaway said:

Never did say what year the bike is. The 2022 has fuel pump problems.

2022 Repsol 301RR! 

well, Good to know! going to contact the link you sent

[lineaway]

7 hours ago, lemur said:

The decompressor is a little tiny (spring loaded) weight that is built right onto the camshaft.  The valve clearance is the only adjustment.  It's a one shot decompressor, if it don't work on the first rotation it won't work.  It's on there so that the engine can complete 2 rotations of the crankshaft and start the fuel pump pumping.  All you are really doing to start the 4RT engine is to spin it up to idle speed, you don't want to jab at the kick starter like a 2-stroke.

Once running the engine will lug down well below the idle start speed before it goes Ker-Puck! and flames out.

100LL avgas contains Tetraethyl Lead ☠️ 

... curious why the 2022 models would have fuel pump problems after they have gone so many years without significant changes.

Absolute best way to trouble-shoot a 4RT problem is to own 2 of them and swap assemblies until you find something that fails.  

 They went to a new pump in 2016. Must have changed suppliers in 2022.

[leosantanalg]

On 8/10/2023 at 8:13 AM, lemur said:

"Before this all started, I was riding one day and when I tried shut off, bike kept running even though the lanyard was disconected. It died after 10 seconds or so."

Would not be the first time the lanyard caused all the problems.

Yes, the air box normally accumulates a small amount of clean engine oil.

Fuel injection sorts itself out when you leave it idle until the fan kicks on.

I'd be tempted to set the valve clearances again, you might not have got them right, have a micrometer handy to check your feeler gauges and to get a feel for the correct clearance.  There is a little tiny decompressor on the exhaust valve side and it needs to be spot on to work and that is the source of hard starting.

I've run higher octane and it does perform better, but they normally run faithful as a Honda on regular octane fuel.

My first 4RT was hard on plugs, every one after that has been good on plugs, I never did find the problem with that first one, I sold it soon after I dropped it in the lake.

"It wouldn't be the first time the lanyard cause all the problems"

Man, aren't you right?? 

Found continuity on the lanyard with it disconected. Just traced it down and it goes to the main harness. 

I have 2 oprions: strip down the main harness with a diagram and find the short or swap the entire harness. Waiting on an answer from Dennis with a peice on new harness.  But so glad I found the problem.  Now everything makes sense. The bike started with weak ignition thus fouling plugs and then the short got worse and bike just doesnt start at all. My only remaini g question is: Could anything else in the electrical system create continuity in that wire other than a bad wire itself?? Thanks a lot all of you 🙏🙏

[leosantanalg]

NEW update (final post)

Problem solved! ended up not being electrical.  after stripping my harness and hitting another wall, I finally decided to call the Montesa USA importer.  Martin is a true Gentleman and carry me through the issue in a matter of minutes.

I did indeed have a "HOT START" issue caused by a defective fuel pump. The 2022 models are experiencing that issue. The good news is Honda is while aware and even has full warranty on that. the best solution however is to upgrade the pump to a Quantum brand fuel pump. Thank You so much all of you that have helped. This community is very knowledgeable and you guys never disappoint!! 

[lsv]

On 8/10/2023 at 10:16 PM, lemur said:

lol ya, with the ministry of environment 

Nothing to do with that, you will have valve sticking issues - I know this from experience............  Have a read..  https://resources.savvyaviation.com/wp-content/uploads/articles_aopa/AOPA_2020-07_why-valves-stick.pdf

[lsv]

On 8/11/2023 at 4:00 AM, leosantanalg said:

How so?? 

https://resources.savvyaviation.com/wp-content/uploads/articles_aopa/AOPA_2020-07_why-valves-stick.pdf

[leosantanalg]

17 hours ago, lsv said:

Nothing to do with that, you will have valve sticking issues - I know this from experience............  Have a read..  https://resources.savvyaviation.com/wp-content/uploads/articles_aopa/AOPA_2020-07_why-valves-stick.pdf

Maybe this will be a topic for future discussion! I can perhaps start a new thread in the general trials forum but just a few pointer before I do:

Have you ever asked your self why they took lead out of every single fuel but did not take it off aviation fuel??? safety is priority over pollution so they made exceptions for aviation.

if you buy pretty much any single person light aircraft in the market today it will come with a bombardier engine (Rotax). that same exact engine goes in all seadoos and skidoos in the market. Identical engine. somehow on seadood and skidoos manual will say Unleaded gas only!! but all aircrafts will say low lead gas only!! 

the internet is full of article of how lead will potentially damage your engine but real scientific articles will explain how lead acts like an extra protection to your engine. for the last almost 10 years I have used strictly aviation gas in everything I own including weed eaters and lawn mowers (pure avgas for 4 strokes and mixed for 2 strokes). I have seen my friends having carburetor problems over and over with ethanol filled gas as my stuff runs always flawless. I had to take flying lessons few years ago just so I could become and airport member and have access to gate and fuel pump inside of the airport! I truly believe on leaded gas and I know I am poluting but that's a different subject. To say that 100ll gas damages engines is just buying in to the narrative. 

[leosantanalg]

18 hours ago, lsv said:

https://resources.savvyaviation.com/wp-content/uploads/articles_aopa/AOPA_2020-07_why-valves-stick.pdf

It's funny how your article blames valve sticking on the lead but in the end of the article when they mention :"how to prevent the valve sticking" they don't even mention to stop using lead. lol  they completely change the subject to "temperature" so basically they re saying is a temperature problem and not lead problem! thanks for the article though 

[TMofCumbria]

Lead was put in petrol for 2 main reasons. To increase the octane rating and thereby prevent knock (pre ignition) and to prevent valve seat recession, that is why when converting a classic car engine to run on unleaded new valves and seats are fitted. I would expect any Japanese made or designed motorcycle engine since 1970s would have no problem running on unleaded.

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[lsv]

On 8/15/2023 at 2:55 PM, leosantanalg said:

It's funny how your article blames valve sticking on the lead but in the end of the article when they mention :"how to prevent the valve sticking" they don't even mention to stop using lead. lol  they completely change the subject to "temperature" so basically they re saying is a temperature problem and not lead problem! thanks for the article though 

It is indeed a temperature related problem and I am glad you've now read the article properly. Whilst you may well get away with using AVGAS on a high revving hard working engine just be warned that you may well have the problems mentioned if used in a trials engine that is just pottering about at low revs - I know I did.

 

On 8/15/2023 at 2:40 PM, leosantanalg said:

Have you ever asked your self why they took lead out of every single fuel but did not take it off aviation fuel??? safety is priority over pollution so they made exceptions for aviation.

As you say, safety reasons due the problem of using Ethanol as a substitute to prevent pre-ignition etc.  But one of the problems IMHO is that it is a misnomer to call it LL when in fact it has a lot more TEL than the leaded fuel we used to be able to buy at the pumps. I believe the LL is just to try and appease the green lobby.....

[lemur]

Not cool to run leaded fuel in a Montesa and that could definitely foul plugs through lead deposits.  

and it's illegal.

 

[leosantanalg]

17 hours ago, lemur said:

Not cool to run leaded fuel in a Montesa and that could definitely foul plugs through lead deposits.  

and it's illegal.

 

if you explain to me why it doesn't foul plugs on airplanes, I might consider changing my mind! being illegal makes it more fun. lol

[lemur]

5 minutes ago, leosantanalg said:

if you explain to me why it doesn't foul plugs on airplanes, I might consider changing my mind! being illegal makes it more fun. lol

You mean all those airplanes that come fitted with 2 spark plugs per cylinder !  Decades ago lead fouled plugs and left visible deposits on every engine I ever ran leaded fuel in.  In the 1960's and 70's we went through spark plugs like they were candy.

 I 'd much rather explain to you the impact of TEL on human and other living things and why you should not be burning TEL in your weed eater today.  ... I'm a field naturalist but I guess you can call me a tree hugger so from where I stand you are not just breaking federal law you are breaking the law of nature  🤔 for fun

[leosantanalg]

11 minutes ago, lemur said:

You mean all those airplanes that come fitted with 2 spark plugs per cylinder !  Decades ago lead fouled plugs and left visible deposits on every engine I ever ran leaded fuel in.  In the 1960's and 70's we went through spark plugs like they were candy.

 I 'd much rather explain to you the impact of TEL on human and other living things and why you should not be burning TEL in your weed eater today.  ... I'm a field naturalist but I guess you can call me a tree hugger so from where I stand you are not just breaking federal law you are breaking the law of nature  🤔 for fun

and that I completely understand! it does pollute and it is harmful, but to twist that and create a narrative that it is bad for your engine is simply a lie. You can make an engine run much smoother by simply switching the E10 to 100ll. Instantly, like it just came from a shop! I have been using avgas on everything I own now except my car (because of catalytic converter) with absolute no issues! I used avgas on my last montesa for the entire time I owned it. This new Montesa, I was using non ethanol but is only 91octane and the bike calls for 95+  the issue I had was due to a defective fuel pump. The question lingers: Why they still use Avgas in aviation?